-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Christian Theune wrote: > Hi Laurence, > > On Wed, 2008-09-03 at 08:06 -0700, Laurence Rowe wrote: >> Backing up a ZODB has always been fairly easy in the past, but with the >> introduction of blobs things have got a little more complex. >> >> How should I create a consistent backup of my Data.fs and blob directory? >> >> My inital guess would be to take a copy of the Data.fs, then take a copy of >> the blob directory to ensure I have all blobs referenced in the Data.fs. >> Would I be able to restore from such a backup safely? (it may contain blobs >> from transactions that were newer than the backed up Data.fs). >> >> This should be safe because committed blobs are immutable and any dangling >> blobfiles would not interfere with the creation of blobs from new >> transactions in the restored zodb, as transaction ids would not overlap. >> >> I would be greatful if anyone could point out holes in my reasoning or has >> experience of this. > > Snapshotting a blob directory after taking a copy of your Data.fs should > be safe, as long as you don't pack in between. > > Note that at the design stage we imagined that blob directories might > become really large making backups unfeasable. For those situations we > handwaved a "very reliable storage" for this directory, like a > self-contained SAN/NAS solution that keeps your data safe.
Assuming we can avoid the race condition induced by packing during the backup (see below), it should be possible to write a script which combines of 'repozo' and 'rsync' in such a way as to get a "pure" copy of the blob directory which corresponds to the repozo dataset. Somethiing like: #!/bin/sh touch .repozo_start /path/to/repozo -B -f var/Data.fs -r backups/ find /path/to/blobs ! -newer .repozo_start |\ rsync -av --include-from=- /path/to/blobs/ backups/blobs/ rm .repozo_start Packing *during* backup creates problems for repozo + blobs, because a pack may cause "old" blob files to be unlined. Furthermore, it is not a use case I think we should support. However, I don't think that FileStorage supports the idea of a "pack lock" which would be acquirable by repozo, so I don't know how to prevent the race. Tres. - -- =================================================================== Tres Seaver +1 540-429-0999 [EMAIL PROTECTED] Palladion Software "Excellence by Design" http://palladion.com -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFIwATJ+gerLs4ltQ4RAm0WAKC/jDUPqBnMTpwkDpBX0mKidGTxvwCghjnM QYnz9dRolzOdvZX2t9fxM3k= =/h4K -----END PGP SIGNATURE----- _______________________________________________ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev
