evms

Langue: en

Version: 09 June 2005 (openSuse - 09/10/07)

Section: 8 (Commandes administrateur)

Sommaire

NAME

evms - The evms command starts the Enterprise Volume Management System (EVMS) Command Line Interpreter (CLI). These command line options control where the EVMS CLI gets commands from and how it interprets those commands. This document begins by explaining the parameter option descriptions and then goes on to explain the commands that can be entered at the CLI's prompt.

SYNOPSIS

evms [-b] [-c] [-d debug-level] [-f filename] [-h] [-m engine-mode] [-n node] [-r parameter] [-s] [-p] [-v[[0-2]]] [-rl parameter ...]]

DESCRIPTION

The CLI does not accept EVMS commands as part of the command line used to invoke it. The parameter options on the command line determine where the CLI gets the commands from and how it interprets those commands. By default, the CLI prompts the user for EVMS commands. To exit the EVMS CLI, type quit or exit.

PARAMETER OPTIONS

The following parameters are available for use during the initial call to invoke the EVMS CLI.

-b
Tells the EVMS CLI to run in batch mode. Any time there is a prompt for input from the user, the default value should be accepted automatically. This is the default behavior with the -f option.
-c
Indicates that changes are not committed to disk until the user exits the CLI. Normally, changes are committed to disk after each individual command is completed, even if there are multiple commands specified on the same command line.
-d
debug-level sets the debug level that controls how much information is logged in /var/log/evms-engine.log. debug-level is specified as one of the following: critical, serious, error, warning, default, details, extra, entry_exit, debug, or everything.
-f
filename tells the CLI to accept input from the file specified by filename. When all of the commands in filename have been processed, the CLI will exit.
-h
Provides help on invoking the EVMS CLI. To get help on commands accepted by the CLI, invoke the Interpreter, enter the word help at the prompt, and press Enter.
-m
engine-mode tells the CLI the mode in which it should open the EVMS Engine. engine-mode is either ReadOnly, ReadWrite, or Daemon. Daemon mode should only be specified when using the CLI to start the EVMS Engine daemon on nodes in a cluster.
-n
node tells the CLI that all commands are intended for the given node name in a cluster.
-p
Tells the CLI to parse commands only. Errors found during parsing will be reported, but the commands will not be executed.
-r
Tells the CLI that the next command line argument is a replacement parameter. See examples below.
-s
Tells the CLI to prompt for a single command line and then exit. Normally, the CLI will prompt for command lines until it receives the quit or exit command.
-v
Enables verbose mode 2.
-v0
Disables verbose mode. Verbose mode 0 allows EVMS Engine status messages to be discarded whenever changes are committed to disk.
-v1
Enables verbose mode 1. Verbose mode 1 allows EVMS Engine status messages to be displayed whenever you commit changes to disk. The messages are displayed one per line on the screen.
-v2
Enables verbose mode 2. Verbose mode 2 allows EVMS Engine status messages to be displayed whenever you commit changes to disk. The messages are displayed using a single line on the screen. This means that the current message is erased, and the next message is displayed in its place.
-rl
tells the EVMS CLI that all of the remaining command line arguments are replacement parameters. Replacement parameters are accessed in EVMS commands using the $(x) notation, where x is a number identifying which replacement parameter to use. Replacement parameters are assigned numbers (starting with 1) as they are encountered on the command line.

Example:


evms -c -f testcase -r sda -r sdb

sda is replacement parameter 1
sdb is replacement parameter 2

Example:


evms -r sda -c -f testcase -rl sdb sdc

sda is replacement parameter 1
sdb is replacement parameter 2
sdc is replacement parameter 3

Example:


evms -c -f testcase -rl sda 100

sda is replacement parameter 1
100 is replacement parameter 2

if testcase contains the command:


allocate:$(1)_freespace, size=$(2)MB

then this command becomes:


allocate: sda_freespace, size=100MB

COMMANDS FOR THE EVMS PROMPT

The following commands can be typed at the EVMS CLI prompt "EVMS: ". This prompt appears when the EVMS CLI is ready to accept a command.

All EVMS CLI commands and key words are case insensitive.

The names and values that you supply are case sensitive.

Any amount of whitespace can appear between commands, delimiters, and values.

ACTIVATE

The Activate command is used to activate volumes or storage objects that are not active. If any of the storage objects that the specified volume or storage object comprises are not active, they will be activated so that the specified volume or storage object can be activated.

The Activate command has the following syntax:

Activate : name

where

Activate
may be abbreviated as act.
name
is the name of a volume or storage object.

Example:
Given a volume /dev/evms/mydata that is not active, activate the volume.


act:/dev/evms/mydata

ADD FEATURE

The Add Feature command adds an EVMS feature to an existing EVMS native volume. The feature is added to the volume by shrinking the filesystem on the volume to make room for the metadata of the new feature. The metadata are then written on the volume. In order to successfully write the metadata for the feature on the volume, EVMS must have a Filesystem Interface Module (FSIM) for the filesystem on the volume, and the FSIM must support filesystem shrinking.

If the volume cannot be unmounted (perhaps because it is root), the FSIM must support on-line shrinking of the filesystem. The filesystem must be able to be shrunk by an amount that is equal to or larger than the metadata of the feature.

CAUTION: The Add Feature command should not be used on volumes that do not have a filesystem (such as databases) as data loss may occur.

The add feature command has the following syntax:

Add Feature : feature = { [name = value [, name = value] ...] } , volume

where

Add Feature
may be abbreviated as af.
feature
is the name of the EVMS feature to add to the volume.
name
is the name of an option accepted by the feature.
value
is an acceptable value for the option name.
volume
is the name of an EVMS volume to which the feature is added.

Example:
The following command adds the feature "My_Drive_Link" to the volume, "My_EVMS_Volume."


af:DriveLink={Name=My_Drive_Link},/dev/evms/My_EVMS_Volume

ADD SEGMENT MANAGER

The Add Segment Manager command is used to assign a segment manager to any disk or segment in the system that does not already have a Segment Manager assigned to it.

The Add Segment Manager command has the following syntax:

Add Segment Manager : segment-mgr = { [name = value [, name = value] ...] } , disk

where

Add Segment Manager
can be abbreviated as asm.
segment-mgr
is the name of the segment manager that is to be assigned to a disk.
name
is the name of an option accepted by the segment manager.
value
is an acceptable value for the option name.
disk
is the name of the disk that the Segment Manager will be assigned to.

The Add Segment Manager command is the same as the Assign command. See the section for the Assign command for an example.

ALLOCATE

The Allocate command is used to allocate regions or segments from blocks of freespace.

The Allocate command has the following syntax:

Allocate : freespace [, name = value] ...

where

Allocate
may be abbreviated as a.
freespace
is the name of a region or segment which represents freespace, such as sdb_freespace1.
name
is the name of an option accepted by the region manager or segment manager which created freespace.
value
is an acceptable value for the option name.

Example:
Given a disk with no partitions that is under the control of the DOS Segment Manager, create a 50 MB segment in an extended partition. The new segment does not have to be bootable.


a:sdb_freespace1,size=50MB,offset=0,primary=false,bootable=false

ASSIGN

The Assign command is used to assign a segment manager to any disk or segment in the system that does not already have a Segment Manager assigned to it.

The Assign command is the same as the Add Segment Manager command.

The Assign command has the following syntax:

Assign : segment-mgr = { [name = value [, name = value] ...] } , disk

where

Assign
can be abbreviated as as.
segment-mgr
is the name of the segment manager that is to be assigned to a disk.
name
is the name of an option accepted by the segment manager.
value
is an acceptable value for the option name.
disk
is the name of the disk that the Segment Manager will be assigned to.

Example:
You have installed a brand new disk into your computer. You wish to partition this disk into multiple partitions using the DOS Segment Manager and the standard Linux partitioning scheme. What must you do before you can partition the disk?

You must assign the DOS Segment Manager to the disk. If EVMS identifies the disk as sdb, the command to do this is:


as:DosSegMgr={TypeByName=Linux},sdb

The previous command will cause the DOS Segment Manager to assume control of the disk sdb and prepare the disk for partitioning. Two new storage objects will result from the Assign command: a metadata segment object and a freespace segment object. The freespace segment, sdb_freespace1, is created to represent the space available on sdb. This space can be divided into data segments (partitions) using Allocate or Create.

CHECK

The Check command performs a consistency check on the filesystem contained within the specified volume. This command is the equivalent of the Linux fsck command.

The Check command has the following syntax:

Check : volume [, name = value] ...

where

Check
can be abbreviated as ch.
volume
is the name of the volume with the filesystem to be checked.
name
is the name of an option supported by the File System Interface Module (FSIM) for the filesystem found on the specified volume.
value
is an acceptable value for option name.

COMMIT

The Commit command can be used when the EVMS CLI is running in alternate mode to force the CLI to save all changes since the last save.

The Commit command is the same as the Save command.

The EVMS CLI can run in either of two modes: default or alternate. The default mode writes to disk any changes made by a command immediately after that command is executed. The alternate mode, which is invoked by using the -c option on the command line that invoked the CLI, holds all changes in memory until the CLI exits. Once the CLI exits, all of the changes being held in memory are written to disk. This alternate mode can significantly improve performance in situations where large command files are executed or complex configurations are used. However, it is not always desirable to hold all changes in memory until the EVMS CLI exits.

When the EVMS CLI is operating in default mode, the Commit command does nothing. When the EVMS CLI is operating in alternate mode, the Commit command forces the EVMS CLI to save all changes it has accumulated. This option effectively gives the user control over when changes are saved and when they are held in memory.

The Commit command has the following syntax:

Commit [: Hold|Release]

where

Hold
tells the EVMS CLI to hold all changes in memory and to commit those changes to disk when the Interpreter exits.
Release
tells the EVMS CLI to write all pending changes to disk immediately and write changes to disk after each command has been completed.

COMMIT WITH THE HOLD KEYWORD

Example:
The EVMS CLI is operating it its default mode, with changes being committed to disk after each command. Change the Interpreter's mode of operation so that changes are held in memory until the Interpreter exits.


commit:hold

COMMIT WITH THE RELEASE KEYWORD

Example:
The EVMS CLI is operating in its alternate mode, with all changes being held in memory until the EVMS CLI exits. Change the EVMS CLI's mode of operation so that changes are committed to disk after each command and write to disk all changes that are currently being held in memory.


commit:release

COMMIT IN ALTERNATE MODE

Example:
The EVMS CLI is operating in its alternate mode, with all changes being held in memory until the EVMS CLI exits. Without changing the mode the Interpreter operates in, force the Interpreter to commit to disk all the changes it is currently holding in memory.


commit

CONVERT

The Convert command has two forms. The first form converts an existing compatibility volume into an EVMS volume. The second form converts an EVMS volume into a compatibility volume.

CONVERTING FROM COMPATIBILITY VOLUMES TO EVMS VOLUMES

The Convert command converts an existing compatibility volume into an EVMS volume by adding EVMS metadata to the compatibility volume. If the compatibility volume does not contain a filesystem, EVMS can add its metadata to the volume and convert it. If the compatibility volume contains a filesystem, EVMS shrinks the filesystem to make room for the EVMS metadata. EVMS must have a filesystem interface module (FSIM) that corresponds to the compatibility volume's filesystem, and the FSIM must support filesystem shrinking.

CAUTION: The Convert command should not be used on compatibility volumes that are being used without a filesystem (for example, databases) as data loss may occur.

The Convert command has the following syntax when converting a compatibility volume to an EVMS volume:

Convert : volume , Name = new-name

where

Convert
may be abbreviated as co.
volume
is the name of the compatibility volume to be converted into an EVMS volume

Name may be abbreviated as the single letter n.

new-name
is the new name for the volume. Please note that the new volume names must be in quotation marks if they contain spaces or any non-alphanumeric characters.

Example:
The following command changes volume /dev/evms/hda3 into an EVMS volume named New_EVMS_Volume.


Co : /dev/evms/hda3 , N = New_EVMS_Volume

CONVERTING FROM EVMS VOLUMES TO COMPATIBILITY VOLUMES

The Convert command converts an existing EVMS volume into a compatibility volume by removing any EVMS metadata on the volume. Currently, this conversion can only occur for EVMS volumes that have no features applied to them.

The Convert command has the following syntax when attempting to convert an EVMS volume into a compatibility volume:

Convert : volume, Compatibility

where

Convert
may be abbreviated as Co.
volume
is the name of the EVMS volume to be converted into a compatibility volume.
Compatibility
is the EVMS keyword used to indicate that a compatibility volume is the type of the resulting volume. Compatibility may be abbreviated as the single letter c.

Example:
The following command changes EVMS volume /dev/evms/Data to a compatibility volume.


Co : /dev/evms/Data , C

CREATE

The Create command is used to create containers, EVMS objects, regions, segments, and volumes. The different items the Create command generates can also be abbreviated as a single letter on the command line.

The syntaxes for each of the Create command options are listed below:

CREATING CONTAINERS

Create : Container , plug-in = { [name = value [, name = value] ...] } , object [, object] ...

where

Create
can be abbreviated as c.
Container
can be abbreviated as c.
plug-in
is the name of the plug-in to use when creating the container.
name
is the name of an option accepted by the plug-in.
value
is an acceptable value for the option name.
object
is the name of a storage object used in the creation of the container.

Example:
Given a system with three available hard drives (sdc, sdd, hdc), use the EVMS LVM Region Manager to combine these disks into a container called Sample_Container with a PE (physical extent) size of 16MB.


c:c,LvmRegMgr={name=Sample_Container,pe_size=16MB},sdc,sdd,hdc

CREATING EVMS OBJECTS

Create : Object , feature = { [name = value [, name = value] ...] } , object [, object] ...

where

Create
can be abbreviated as c.
Object
can be abbreviated as o.
feature
is the name of the EVMS Feature plug-in to use when creating the EVMS object.
name
is the name of an option accepted by the region manager.
value
is an acceptable value for the option name.
object
is the name of a region, segment, disk, or EVMS object to be used in the creation of the new EVMS object.

Example:
Given a system with a volume /dev/evms/Source, and an available segment sdb5, create a snapshot object called "My_Snapshot_Object" using the EVMS SnapShot feature. /dev/evms/Source is the source of the snapshot, and sdb5 is the backing store for the snapshot.


c:o,Snapshot={original=/dev/evms/Source,snapshot=My_Snapshot_Object},sdb5

CREATING REGIONS

Create : Region , region-mgr = { [name = value [, name = value] ...] } , object [, object] ...

where

Create
can be abbreviated as c.
Region
can be abbreviated as r.
region-mgr
is the name of the Region Manager plug-in you want to use.
name
is the name of an option accepted by the region manager.
value
is an acceptable value for the option name.
object
is the name of a region, segment, or disk to be used in the creation of the new region.

CREATING SEGMENTS

Create : Segment , freespace [, name = value] ...

where

Create
can be abbreviated as c.
Segment
can be abbreviated as s.
freespace
is the name of a segment representing freespace.
name
is the name of an option accepted by the segment manager that created the freespace.
value
is an acceptable value for the option name.

Example:
Given a disk that is under the control of the DOS Segment Manager, has no primary partitions, and has a 200 MB freespace segment called sdb_freespace1, create a 50 MB logical segment. The new segment does not have to be bootable.


c:s,sdb_freespace1,size=50MB,offset=0,primary=false,bootable=false

CREATING COMPATIBILITY VOLUMES

Create : Volume , object , Compatibility

where

Create
can be abbreviated as c.
Volume
can be abbreviated as v.
object
is the name of the disk, segment or region that will become a volume.

Example:
Given a system with an unused segment sda3, turn this segment into a compatibility volume.


c:v,sda3,c

CREATING EVMS VOLUMES

Create : Volume , object , Name = name

where

Create
can be abbreviated as c.
Volume
can be abbreviated as v.
object
is any disk, segment, region, or EVMS object that is not already a volume or a part of a volume, storage object, or storage container.
name
is the name that you would like the volume to have. This name must be unique throughout the system, and the volume, once created, will be known as /dev/evms/name.

Example:
Given a system with an unused segment sda3, make sda3 an EVMS volume known as Widow_Maker.


c:v,sda3,n=Widow_Maker

DEACTIVATE

The Deactivate command is used to deactivate volumes or storage objects that are active. When a storage object is deactivated, all of the storage objects and volumes that are built using the specified storage object will also be deactivated, since active objects and volumes cannot be built from inactive objects.

The Deactivate command has the following syntax:

Deactivate : name

where

Deactivate
may be abbreviated as deact.
name
is the name of a volume or storage object.

Example:
Given a volume /dev/evms/mydata that is active, deactivate the volume.


deact:/dev/evms/mydata

DELETE

The Delete command deletes a volume, container EVMS object, region, or segment from the system.

The Delete command has the following form:

Delete : name

where

Delete
can be abbreviated as d.
name
is the name of the volume, container, EVMS object, region, or segment that is to be deleted.

ECHO

The Echo command echoes a string to the standard output. Echo allows the user to output user defined text from an EVMS command file.

The Echo command has the following syntax:

Echo : String

where

String
is any sequence of ASCII characters except quotation marks. A string should be enclosed in quotation marks if it contains any non-alphabetic or non-numeric characters or spaces. If a quotation mark is embedded in the string as part of the string, then quotation marks should also surround the embedded string, as in the example below:

Example:


Echo : "This is a ""sample"" string with embedded quotation marks."

EXIT

The Exit command is used to exit the EVMS CLI.

The Exit command is the same as the Quit command.

EXPAND

The Expand command is used to increase the size of a volume, storage container, or storage object.

Listed below are the two syntaxes of the expand command. The first syntax is for increasing the size of storage containers. The second syntax of Expand is for increasing the size of volumes and storage objects.

Increasing the Size of a Storage Container

Storage Containers are expanded by adding segments or regions to them. When expanding containers, the Expand command has the following syntax:

Expand : container , object [, object] ...

where

Expand
can be abbreviated as e.
container
is the name of the container to expand.
object
is the name of a disk. segment or region to add to the container specified by container.

Increasing the Size of a Volume or Storage Object

An EVMS volume or storage object can be comprised of one or more EVMS objects, regions, segments, or disks. Whether a volume or storage object can be expanded or not depends on how it is constructed. For example, if a volume consists of a single segment with no EVMS features applied to it, then it can only be expanded if the Segment Manager that created the segment can increase the size of that segment. EVMS allows complete control over how a volume is expanded.

A more complicated volume may have several ways to expand. For example, a volume created from several segments using EVMS Drive Linking can be expanded by increasing the size of the last segment in the drive link. You can also expand the volume by using EVMS Drive Linking to add another segment to the volume. When a volume can be expanded in multiple ways, we say that the volume has multiple expansion points.

To expand a volume, you must specify which expansion point to use. The same is true for storage objects. In the example from the paragraph above, there are two expansion points. One expansion point is the EVMS object created by EVMS Drive Linking. This EVMS object could be expanded by adding another segment to it. The second expansion point is the last segment used in the EVMS object formed by EVMS Drive Linking. While the other segments used to create this EVMS object may be capable of being expanded, EVMS Drive Linking allows only the last segment to be expanded.

To find the expansion points for a storage object or volume, use the Query Expand Points command. Once you know the expansion points for a volume or storage object, these points can be used to expand the volume or storage object.

When increasing the size of a volume or storage object the Expand command has the following syntax:

Expand : expansion-point [, name = value] ... [, object] ...

where

Expand
can be abbreviated as e.
expansion-point
is the name of an expansion point as provided by the Query Expand Points command.
name
is the name of an option supported by the plug-in module that controls Expansion-Point.
value
is an acceptable value for the option Name.
object is the name of an acceptable EVMS object, region, segment,
freespace, or disk to use for expanding the volume.

Example:
This example assumes that there is a volume created from three segments using EVMS Drive Linking. The three segments are sda1, sdb1, and sdc1. The EVMS object created by EVMS Drive Linking is called DL1, and the volume is called /dev/evms/Sample_Volume. The segment sdc1 is controlled by the DOS Segment Manager (DosSegMgr), and has a 50 MB block of freespace (sdc_freespace1) adjacent to it on the disk. Also, there is an unused 200 MB segment known as hda7 available in the system. The Query Expand Points command indicates that this volume has two expansion points: DL1 and sdc1. Expand this volume by 250 MB.

First, we must consider the order in which we will use the expand points to expand the volume. Currently, sdc1 is an expand point. Since EVMS Drive Linking allows only the last segment it is linking to be expanded, sdc1 must be the last segment that EVMS Drive Linking uses to create DL1. If we add hda7 to DL1, then hda7 will become the last segment used in DL1, and sdc1 will not be an expansion point anymore. Without being able to expand sdc1, we will not be able to reach our goal of expanding the volume by 250 MB. However, expanding sdc1 has no effect on our ability to add hda7 to DL1, so if we expand sdc1 before we add hda7 to DL1, we will be able to achieve our goal of expanding the volume by 250 MB. Completing our expansion will require two commands. First, to expand sdc1, we use:


e:sdc1,size=50MB,sdc_freespace1

Now, to add hda7 to DL1, use the command:


e:DL1,hda7

The resulting change is that the volume is 250 MB larger than before.

FORMAT

The Format command creates a filesystem on a volume. This is the equivalent of the Linux mkfs command.

The Format command is the same as the Mkfs command.

The Format command has the following syntax:

Format : FSIM = { [name = value [, name = value] ...] } , volume

where

Format
can be abbreviated as f.
FSIM
is the name of a File System Interface Module recognized by EVMS. The specified FSIM is used to create the filesystem on the volume specified by volume. Normally there is one FSIM for each filesystem, so specifying the FSIM is the same as specifying the filesystem. In cases where one FSIM supports more than one filesystem, you can use an option to specify which filesystem should be created.
name
is the name of an option supported by the FSIM for the filesystem found on the specified volume.
value
is an acceptable value for the option Name.
volume
is the name of the volume where the filesystem is to be created.

HELP

The CLI offers help on the essential commands. To obtain detailed help on an EVMS command, type the following:

Help : command

The CLI supports the following commands:

Activate
activates volumes and storage objects.
Add Feature
adds the specified feature to an existing EVMS volume.
Add Segment Manager
attempts to add the specified segment manager to a disk or segment. (Same as Assign.)
Allocate
allocates regions and segments from freespace.
Assign
assigns a segment manager to a disk or segment. (Same as Add Segment Manager.)
Check
performs an fsck on a volume.
Commit
causes any changes that have not yet been written to disk to be written to disk. (Same as Save.)
Convert
converts a compatibility volume into an EVMS volume or an EVMS volume into a compatibility volume.
Create
creates volumes, EVMS objects, regions, segments, and containers.
Deactivate
deactivates volumes and storage objects.
Delete
deletes volumes, containers, EVMS objects, regions, and segments.
Echo
echoes a string to standard output.
Exit
exits the EVMS CLI. (Same as Quit.)
Expand
expands the size of volumes, containers, EVMS objects, regions, and segments.
Format
performs a mkfs operation on a volume. (Same as Mkfs.)
Help
provides help on a specific EVMS command.
Mkfs
creates a filesystem on a volume. (Same as Format.)
Modify
modifies some of the options associated with a container, EVMS object, region, segment, or disk.
Mount
mounts a volume on a directory.
Probe
causes EVMS to check the system for hardware changes.
Query
gathers information about the volumes, containers, EVMS objects, regions, and segments in the system.
Quit
exits the EVMS CLI. (Same as Exit.)
Remove
removes the segment manager assigned to a disk or segment.
Rename
changes the names of volumes.
Replace
replace a storage object with another storage object.
Revert
deconstructs a volume or storage object a layer at a time.
Save
causes any changes which have not yet been written to disk to be written to disk. (Same as Commit.)
Set
modifies some of the options associated with a container, EVMS object, region, segment, or disk.
Shrink
reduces the size of volumes, containers, EVMS objects, regions, and segments.
Task
allows access to plug-in specific functions.
Unformat
removes a filesystem from a volume. The contents of the filesystem are lost.
UnMkfs
removes a file system from a volume. The contents of the volume are lost.
Unmount
unmounts a volume.

Example:
Get detailed help on the Create command.


Help: Create

MKFS

The mkfs command creates a filesystem on a volume.

The Mkfs command is the same as the Format command.

The mkfs command has the following syntax:

mkfs : FSIM = { [name = value [, name = value] ...] } , volume

where

FSIM
is the name of a File System Interface Module recognized by EVMS. The specified FSIM is used to create the filesystem on the volume specified by volume. Normally there is one FSIM for each filesystem, so specifying the FSIM is the same as specifying the filesystem. In cases where one FSIM supports more than one filesystem, you can use an option to specify which filesystem should be created.
name
is the name of an option supported by the FSIM for the filesystem found on the specified volume.
value
is an acceptable value for the option name.
volume
is the name of the volume where the filesystem is to be created.

MODIFY

The Modify command changes options on EVMS objects, regions, containers, segments, or disks. If a Query command which returns EVMS objects, regions, containers, segments, or disks is executed using the List Options pseudo filter, then the changeable options for each item returned will be listed with that item.

The Modify command has the following syntax:

Modify : item , name = value [, name = value] ...

where

item
is the name of a EVMS object, region, container, segment or disk whose options are to be changed.
name
is the name of an option that can be set for item.
value
is an acceptable value for option name.

MOUNT

The Mount command mounts a volume on a directory.

The Mount command has the following syntax:

Mount : volume , mount-point [, mount-options]

where

volume
is the name of the volume to be mounted.
mount-point
is the name of the directory on which to mount the volume.
mount-options
is a string of options to be passed to the mount command.

PROBE

The Probe command is used to probe the system for hardware changes. This command is useful when the media in a removable media device has been changed. The Probe command will commit any pending changes (from prior commands) to disk before probing the system for hardware changes, even if the -c option was used when invoking the CLI. Probe can be abbreviated as a single letter p on the command line.

QUERY

The Query command is used to obtain information about the states of the volumes, EVMS objects, regions, containers, segments, and disks in the system.

The Query command has several different syntaxes. One syntax is used for gathering information about the volumes, EVMS objects, regions, containers, segments, disks, and plug-in modules in the system. The other syntax for the Query command is used for gathering information related to various tasks that you can perform on items in the system.

To gather information about volumes, containers, EVMS objects, regions, segments, disks, or plug-in modules, use this syntax of the Query command:

Query : data-type [, filter] ...

where

Query
can be abbreviated as the single letter q.
data-type
is either:
plug-ins
(abbreviated as p)
volumes
(abbreviated as v)
containers
(abbreviated as c)
objects
(abbreviated as o)
regions
(abbreviated as r)
segments
(abbreviated as s)
disks
(abbreviated as d)
filter
is one of the available filters for the type of data being returned. A filter restricts what is returned based upon some characteristic of the items being returned. The available filters for a query depend upon data-type.

When processing a query like the one above, the CLI gathers items in the system of data-type. The interpreter puts these items into a list called the Return Values List. Each of the filters you specified examines the Return Values List and removes any items that do not fit the filter criteria. Once all of the filters have processed the Return Values List, the CLI displays the items that remain in the Return Values List.

NOTE: Not all filters will work with every query. Furthermore, some filters may be mutually exclusive. See the EVMS Command Line Grammar to determine which combinations of filters are allowed for a particular query.

SUPPORTED FILTERS

The EVMS Command Line Interpreter supports the following filters:

Plug-in Type Filter

The plug-in Type filter is only available when data-type is equal to plug-ins. This filter removes from the Return Values List any entries for plug-in modules that are not of the type specified.
The syntax for this filter is:
Type = plugin-type
where
Type
can be abbreviated as the single letter t.
plugin-type
is one of the following:
device manager
(abbreviated as d)
segment manager
(abbreviated as s)
region manager
(abbreviated as r)
feature
(abbreviated as f)
filesystem interface module
(abbreviated as FSIM)
cluster management
(abbreviated as CM)

Plugin Filter

The Plugin filter is available when data-type is either volumes, objects, regions, containers, segments, disks, or plug-ins. This filter removes any entries that have no association with the specified plug-in module from the Return Values List.
*
For volumes and storage objects, any volume that was created without the use of the specified plug-in module is removed from the Return Values List.
*
For regions, any region not created by the specified plug-in module is removed from the Return Values List.
*
For containers, any container not created by the specified plug-in module is removed from the Return Values List.
*
For segments, any segment not created by the specified plug-in module is removed from the Return Values List.
*
For disks, any disk not claimed by the specified plug-in module is removed from the Return Values List.
*
For plug-in modules, all plug-in modules other than the one specified are removed from the Return Values List.

The syntax of the Plugin filter is:

Plugin = plug-in

where

Plugin
can be abbreviated as the single letter p.
plug-in
is the name or ID number of a plug-in module.

Volume Filter

The Volume filter is available when data-type is either plug-ins, objects, regions, segments, or disks. This filter removes from the Return Values List any item that was not used in the construction of the specified volume.
The syntax for the Volume filter is:
Volume = volume
where
Volume
can be abbreviated as the single letter v.
volume
is the fully qualified name of a volume.

Object Filter

The Object filter is available when data-type is either plug-ins, volumes, objects, regions, segments, or disks. This filter removes from the Return Values List items that either did not create the specified object, or were created without using the specified storage object. The Object filter removes from the Return Values List each of the following:
*
For plug-ins, the filter removes all plug-in modules except for those that are needed to create the specified storage object.
*
For volumes, the filter removes any volume that does not use the specified storage object.
*
For objects, regions, segments, and disks, the filter removes any storage object that was not used in the creation of the specified storage object.

The syntax of the Object filter is:

Object = name

where

Object
can be abbreviated as the single letter o.
name
is the name of an object that EVMS has discovered.

Container Filter

The Container filter is available when data-type is either plugins, volumes, objects, regions, or segments.
The list below explains what the Container filter removes from the Return Values List when data-type is one of the following:
*
For plug-ins, the filter removes all plug-ins that were not used to create the container.
*
For volumes, the filter removes any volume constructed without using a region from the specified container.
*
For objects, the filter removes any object constructed without using a region from the specified container.
*
For regions, the filter removes any regions that do not come from the specified container.
*
For segments, the filter removes any segment that was not used to create the container.

The syntax of the Container filter is:

Container = name

where

Container
can be abbreviated as the single letter c.
name
is the name of a container that EVMS has discovered.

Region Filter

The Region filter is available when data-type is either volumes, objects, or containers.
The list below explains what the Region filter removes from the Return Values List when data-type is one of the following:
*
For volumes, this filter removes any volume constructed without using the specified region.
*
For objects, this filter removes any object constructed without using the specified region.
*
For containers, this filter removes any container other than the one it came from.

The syntax of the Region filter is:

Region = name

where

Region
can be abbreviated as the single letter r.
name
is the name of a region that EVMS has discovered.

Disk Filter

The Disk filter is available when data-type is segments. This filter removes from the Return Values List any segment which does not lie on the specified disk.
The syntax of the Disk filter is:
Disk = name
where
Disk
can be abbreviated as the single letter d.
name
is the name of a disk that EVMS knows about.

Size Filters

There are three size filters: less than, greater than, and equal to. These filters are available when data-type is either volumes, containers, objects, regions, segments, or disks. These filters remove items from the Return Values List based upon their size.
The Less Than filter has the following syntax:
LT n unit
where
n
is a positive integer or 0.
unit
is either KB, MB, GB, or TB.

The Greater Than filter has the following syntax:

GT n unit

where

n
is a positive integer or 0.
unit
is either KB, MB, GB, or TB.

The Equal filter has the following syntax:

EQ n unit , precision

where

n
is a positive integer or 0.
unit
if specified, must be either KB, MB, GB, or TB.
precision
is a positive integer. precision indicates how "sloppy" a match to make. If no unit is specified, then precision is interpreted to be a percentage. If precision is seen as a percentage, the value is considered to be equal to n as long as the value is within n plus or minus precision percent of n. If a unit (KB, MB, GB, TB) is specified for precision, then a value is considered equal to n if the value is within the range of n - precision to n + precision.

Freespace Filter

The Freespace filter removes any items that do not contain freespace from the Return Values List. This filter is only useable when data-type is containers.
The syntax of the Freespace filter is:
Freespace , size-filters
where
Freespace
can be abbreviated as the single letter f.
size-filters
These filters are the same Size filters used with other filters, only now, instead of using the size of the containers for comparisons, the size-filters will use the freespace in the containers for comparisons.

Expandable Filter

The Expandable filter is available when data-type is either volumes, regions, objects, or segments. This filter removes any items that cannot be expanded from the Return Values List.
The syntax of this filter is:
Expandable
where
Expandable
can be abbreviated as the single letter e.

Shrinkable Filter

The Shrinkable filter is available when data-type is either volumes, regions, objects, or segments. This filter removes any items that cannot be shrunk from the Return Values List.
The syntax of this filter is:
Shrinkable
where
Shrinkable
can be abbreviated as the single letter s.

Unclaimed Filter

The Unclaimed filter is available when data-type is disks. This filter removes all disks which have been claimed by a Segment Manager plug-in module (disks that have a recognized partitioning scheme in place) from the Return Values List. The disks left in the Return Values List will either have no partitioning scheme, or the partitioning scheme is unrecognized.
The syntax of this filter is:
Unclaimed
where
Unclaimed
can be abbreviated as the single letter u.

List Options Pseudo Filter

List Options is treated like a filter, but it actually causes the CLI to list what can be done with each item in the Return Values List.
The syntax of this filter is:
List Options
where
List Options
can be abbreviated with the letters lo.

SAMPLE QUERIES USING FILTERS

*
To query the plug-ins in the system and their options:

q:p,lo
*
To query only the region manager plug-ins in the system and their options:

q:p,t=r,lo
*
To query the volumes in the system:

q:v
*
To query the volumes in the system over 1GB in size:

q:v,gt 1GB
*
To query the storage objects in the system:

q:o
*
To query the segments in the system that reside on disk sda:

q:s,d=sda
*
To query the segments in the system that belong to the container lvm/MyStuff, are over 500 MB in size and less than 2 GB in size, and come from disk sda:

q:s,c=lvm/MyStuff,GT 500MB,lt 2GB,d=sda

SPECIALTY QUERY COMMANDS

The following commands allow for specialty queries.

Query Children

The Query Children command returns items that were used to create the specified item. For example, the children of a storage object are the EVMS objects, regions, disks, or segments that were used to create the specified storage object.
The syntax of this command is:
Query : Children , name
where
Children
can be abbreviated as chi.
name
is the name of a volume, EVMS object, region, segment, or container.

Query Parent

The Query Parent command returns the item (if there is one) that uses the specified item. For example, if a storage object is specified, then this command will return the volume or storage object which was created using the specified storage object, if such a volume or storage object exists. The syntax of this command is:
Query : Parent , name
where
Parent
can be abbreviated as par.
name
is the name of a storage object, region, segment, container, or disk.

Query Expand Points

The Query Expand Points returns the expansion points for a volume or storage object. The expansion points for a volume or storage object are those entities within the volume or storage object that can be expanded without causing a loss of data.
The syntax of this command is:
Query : Expand Points , name
where
Expand Points
can be abbreviated as ep.
name
is the name of a storage object or volume.

Query Shrink Points

Query Shrink Points returns the shrink points for a volume or storage object. The shrink points for a volume or storage object are those entities within the volume or storage object that can be shrunk without causing a loss of data. The syntax of this command is:
Query : Shrink Points , name
where
Shrink Points
can be abbreviated as sp.
name
is the name of a Storage Object or Volume.

Query Extended Info

Query Extended Info command allows access to any additional information that may be available for a plug-in module, a EVMS object, a region, a segment, a disk, or a container. The syntax of this command is:
Query : Extended Info , name [, field]
where
Extended Info
can be abbreviated as ei.
name
is the name of a EVMS object, disk, region, segment, container, or plug-in module. It can also be the numeric ID of a plug-in module.
field
is the name of a specific piece of extended information. Extended Information is grouped into fields. Each field has a name and one or more values associated with it.

Query Acceptable

The Query Acceptable allows you to discover which EVMS objects, regions, segments, or disks are acceptable for creating or expanding a volume, EVMS object, region, or segment. The command works as follows:
When you create containers, objects, or regions, specify the following: the plug-in module being used, the values for the options that the plug-in module is to use when creating the container/object/region, and the EVMS objects, regions, segments, or disks that you have decided to use. The query will return any EVMS objects, regions, segments, or disks that are still available and acceptable for use in creating the container/object/region.

Example:
An example of using this command would be to determine what segments should be used to create a software RAID 5 storage object. Initially, no segments have been selected, so all unused segments in the system might be available and might be returned by this query. Choose an initial segment, which causes all segments on the same drive to not be acceptable anymore.
To find out what segments are still available, use this query again and specify the segments that have already been chosen. This query will return all of the segments that might still be chosen. To see which segments are still available, choose another segment, and use this query again, specifying all of the segments that have already been chosen in the order in which they were chosen. You can use this iterative process to build an ordered list of segments. From this list you can see what segments you can use in an actual create command to create the desired software RAID 5 storage object.

When expanding volumes or storage objects, specify the volume or storage object to be expanded along with any EVMS objects, segments, regions, or disks that you have already chosen to use in the expansion. This query will return the EVMS objects, regions, segments, or disks that you can still select and use to expand the specified volume or storage object.

As described above, an iterative process can be used to build an ordered list of the EVMS objects, regions, segments, or disks that can be used to expand the specified volume or storage object with an actual expand command.

The Query Acceptable command has two syntaxes: one for use with Create, the other for use with Expand.


Create
For determining what is acceptable for use with Create, use the following syntax:
Query : Acceptable, Create , type, plug-in = { [name = value [, name = value] ...] } , object [, object] ...
where
Acceptable
can be abbreviated as the single letter a.
Create
can be abbreviated as the single letter c.
type
is either object, region, or container. object can be abbreviated as a single letter o. region can be abbreviated as a single letter r. container can be abbreviated as a single letter c.
plug-in
is the name or ID number of the plug-in module to use when creating type.
name
is the name of an option supported by plug-in.
value
is a legitimate value for the option name.
object
is the name of a EVMS object, region, segment or disk which is to be used to create type.

Expand

For determining what is acceptable for use with Expand, use the following syntax:
Query : Acceptable , Expand , expansion-point , object [, object] ...
where
Acceptable
can be abbreviated by the single letter a.
Expand
can be abbreviated by the single letter e.
expansion-point
is the name of a volume or storage object that is to be expanded.
object
is the EVMS name of a EVMS object, region, segment or disk which is to be used when expanding expansion-point.

QUIT

The Quit command is used to exit the EVMS CLI.

The Quit command is the same as the Exit command.

REMOVE

The Remove command is used to remove a segment manager from a disk. A segment manager can only be removed from a disk when all of the data segments on that disk have been deleted. The Remove command causes a Segment Manager to remove its metadata from the disk, thereby leaving an empty disk. The empty disk can be used directly, or another segment manager can be assigned to it.

The Remove command has the following syntax:

Remove : name

where

Remove
can be abbreviated as rem.
name
is the name of a disk that EVMS knows about.

Example:
This example will assume that you have a disk, sdb, and that this disk has several partitions on it that are managed by the DOS Segment Manager. The data segments on disk sdb are not being consumed by any EVMS object and could be deleted. Assume that you have a drive link that is aggregating several disks and that you would like to expand the drive link with the addition of disk sdb. In order for disk sdb to become an acceptable object for expanding the drive link, you must remove the segment manager and all the partitions from the disk.

After deleting all the data segments on disk sdb, use the following command:


Rem:sdb

RENAME

The Rename command is used to change the name of an EVMS volume.

The Rename command has the following syntax:

Rename : volume , Name = new-name

where

Rename
can be abbreviated as the single letter r.
volume
is the name of the volume that needs to be changed.
Name
can be abbreviated as the single letter n.
new-name
is the new name for the volume. Please note that the new volume name must be in quotation marks if it contains spaces or any non-alphanumeric characters.

Example:
Rename the volume /dev/evms/John to /dev/evms/Fred.


r:/dev/evms/John,n=Fred

REVERT

The Revert command strips away the topmost layer of an EVMS volume or storage object and restores it to its previous EVMS state. Thus, an EVMS Volume will revert to the EVMS Storage Object that it came from.

The Revert command has the following syntax:

Revert : name

where

Revert
can be abbreviated as rev.
name
is the name of the volume or storage object to revert.

Example:
In this example, assume that you have just created a storage object named "Fred" from a storage object named "Barney." Fred is a complicated storage object that would take time to recreate. However, after creating Fred, you find out that you applied the wrong feature to Barney to create Fred. To remove the feature that was applied to Barney to create Fred without having to delete Fred and start from scratch, type the following command:


Rev:Fred

The Revert command will strip away the top most feature on Fred undoing the creation of Fred and leaving Barney.

SAVE

The Save command can be used when the EVMS CLI is running in alternate mode to force the CLI to save all changes since the last save.

The Save command is the same as the Commit command.

The EVMS CLI can run in either of two modes: default or alternate. The default mode writes to disk any changes made by a command immediately after that command is executed. The alternate mode, which is invoked by using the -c option on the command line that invoked the CLI, holds all changes in memory until the CLI exits. Once the CLI exits, all of the changes being held in memory are written to disk. This alternate mode can significantly improve performance in situations where large command files are executed or complex configurations are used. However, it is not always desirable to hold all changes in memory until the EVMS CLI exits.

When the EVMS CLI is operating in default mode, the Save command does nothing. When the EVMS CLI is operating in alternate mode, the Save command forces the EVMS CLI to save all changes it has accumulated. This option effectively gives the user control over when changes are saved and when they are held in memory.

The Save command has the following syntax:

Save [: Hold|Release]

where

Hold
tells the EVMS CLI to hold all changes in memory and to save those changes to disk when the Interpreter exits.
Release
tells the EVMS CLI to write all pending changes to disk immediately and write changes to disk after each command has been completed.

SAVE WITH THE HOLD KEYWORD

Example:
The EVMS CLI is operating it its default mode, with changes being saved to disk after each command. Change the Interpreter's mode of operation so that changes are held in memory until the Interpreter exits.


save:hold

SAVE WITH THE RELEASE KEYWORD

Example:
The EVMS CLI is operating in its alternate mode, with all changes being held in memory until the EVMS CLI exits. Change the EVMS CLI's mode of operation so that changes are saved to disk after each command and write to disk all changes that are currently being held in memory.


save:release

SAVE IN ALTERNATE MODE

Example:
The EVMS CLI is operating in its alternate mode, with all changes being held in memory until the EVMS CLI exits. Without changing the mode the Interpreter operates in, force the Interpreter to save to disk all the changes it is currently holding in memory.


save

SET

The Set command changes options on EVMS objects, regions, containers, segments, or disks. If a Query command which returns EVMS objects, regions, containers, segments, or disks is executed using the List Options pseudo filter, then the changeable options for each item returned will be listed with that item.

The Set command has the following syntax:

Set : item , name = value [, name = value] ...

where

item
is the name of a EVMS object, region, container, segment or disk whose options are to be changed.
name
is the name of an option that can be set for item.
value
is an acceptable value for option name.

SHRINK

The Shrink command reduces the size of a volume, storage object, or storage container.

Reducing the Size of a Storage Container

You can reduce the size of a storage container by removing one or more of the segments or regions it contains.

The Shrink command has the following syntax when used with storage containers:

Shrink : container , object [, object] ...

where

Shrink
can be abbreviated as the letter s.
container
is the name of the storage container to shrink.
object
is the name of a segment or region in the storage container that is to be removed from the storage container.

Reducing the Size of a Volume or Storage Object

An EVMS volume or storage object can be comprised of one or more EVMS objects, regions, segments, or disks. Whether or not a volume or storage object can be shrunk depends upon how it is constructed. For example, if a volume consists of a single segment with no EVMS features applied to it, then whether or not you can shrink the volume depends upon whether the segment manager that created that segment can decrease the size of that segment.

You can shrink a more complicated volume in several ways. For example, you can shrink a volume created from several segments using EVMS Drive Linking by decreasing the size of one of the segments being linked. You could also use EVMS Drive Linking to remove a segment from the drive link. If you could do both options to shrink the volume, we say that the volume has multiple shrink points, because there are multiple ways in which the volume can be shrunk.

EVMS gives you control over how a volume is shrunk. To shrink a volume, you need to specify which shrink point to use. The same is true for storage objects. If there are two shrink points, the first would be the EVMS object created by EVMS Drive Linking. This storage object could be shrunk by removing a segment from it. The second shrink point would be the last segment used in the EVMS object formed by EVMS Drive Linking. While you might be able to shrink the other segments used to create this EVMS object, EVMS Drive Linking prohibits shrinking these segments.

To find the shrink points for a storage object or volume, use the Query Shrink Points command. Once the shrink points for a volume or storage object are known, they can be used with this command to shrink the volume or storage object.

The Shrink command has the following syntax:

Shrink : shrink-point [, name = value] ... [, object] ...

where

shrink-point
is the name of a shrink point as provided by the Query Shrink Points command.
name
is the name of an option supported by the plug-in module that controls shrink-point.
value
is an acceptable value for option name
object
is the name of an acceptable EVMS object, region, segment, or disk to be shrunk or removed from the volume.

Example:
This example assumes that you have a volume created from three segments using EVMS Drive Linking. The three segments used are sda1, sdb1, and sdc1. The EVMS object created by EVMS Drive Linking is called DL1, and the volume is called /dev/evms/Sample_Volume. The segment sdc1 is controlled by the DOS Segment Manager (DosSegMgr), and it can be shrunk by 50 MB. The Query Shrink Points command returns DL1 and sdc1 as the available shrink points. Shrink the volume by 50 MB.


s:sdc1,size=50MB,sdc1

TASK

The Task command accesses functions specific to an EVMS plug-in module. The Task command can be used directly on an EVMS plug-in module, or it can be used on a volume, EVMS object, region, segment, or container. When used on a EVMS object, region segment, or container, the command is directed to the plug-in module that owns the EVMS object, region, segment, or container. When used on a volume, the command is directed to the File System Interface Module associated with the volume.

The Task command has the following syntax:

Task : task-name , target [, name = value] ... [, source] ...

where

task-name
is the name of the task as defined by the EVMS plug-in that is expected to perform the task.
target
is the volume, object, region, segment, container, or plug-in that the task is to be performed on.
name
is the name of an option accepted by the plug-in that controls the specified target.
value
is an acceptable value for option name.
source
is the name of a volume, object, region, segment to use when performing the specified task on the specified target.

UNFORMAT

The Unformat command destroys the filesystem within the specified volume. This process is typically completed by overwriting the metadata for the filesystem with zeros. All data on the filesystem is lost.

The Unformat command has the following syntax:

Unformat : volume

where

Unformat
can be abbreviated by the single letter u.
volume
is the name of the volume whose filesystem is to be destroyed.

UNMKFS

The Unmkfs command destroys the filesystem within the specified volume. This process is typically completed by overwriting the metadata for the filesystem with zeros. All data on the filesystem is lost.

The Unmkfs command has the following syntax:

Unmkfs : volume

where

Unmkfs
can be abbreviated by the single letter u.
volume
is the name of the volume whose filesystem is to be destroyed.

UNMOUNT

The Unmount command unmounts a volume.

The Unmount command has the following syntax:

Unmount : volume

where

volume
is the name of the Volume to be unmounted.