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dumpfile

NAME

dumpfile - Format of a dump file

DESCRIPTION

The dump files are formatted as tagged byte streams. Each piece of the dump is marked by a tag byte, a number between 1 and 20. Each piece may also be broken into subpieces, each marked by a letter of the alphabet. Each subpiece is uniquely marked, but tags can be reused in different parts of the dump.

The first 60 bytes of the dump contain header information. This header info identifies which backup volume was used to create the dump, and when and from which volume the backup clone was created. It also indicates whether the dump was incremental, and provides information to be used later in placing this dump in the proper sequence for merging. Following the dump header is the volume information structure used by the Coda internals. Following this are two sequences of vnodes, one for directories and one for files. Each sequence consists of a header and a stream of vnodes.

The vnode sequence header contains the number of vnodes and the size of the vnode list. These numbers are not necessarily the same since not every list needs to have a vnode on it and some lists may have more than one. This is an artifact of the way vnodes are stored in the Coda servers.

After these two fields comes a list of vnodes. Each vnode consists of two parts, the first is the meta information associated with the file or directory and the second is the data for that vnode. This data could either be directory pages or file data. The first word after the tag for the file or directory data is a count of bytes or directory pages. For directory vnodes, the access list for that directory is included as part of the meta information.

SEE ALSO

backup (8), dumplist (5), volutil (8)

AUTHOR

Joshua Raiff, 1993, Taken from system adminstrators guide.