On 18/03/2010 13:12, joerg.schill...@fokus.fraunhofer.de wrote:
Darren J Moffat<darren.mof...@oracle.com> wrote:
So exactly what makes it unsuitable for backup ?
Is it the file format or the way the utility works ?
If it is the format what is wrong with it ?
If it is the utility what is needed to fix that ?
This has been discussed many times in the past already.
If you archive the incremental "star send" data streams, you cannot
extract single files andit seems that this cannot be fixed without
introducing a different archive format.
That assumes you are writing the 'zfs send' stream to a file or file
like media. In many cases people using 'zfs send' for they backup
strategy are they are writing it back out using 'zfs recv' into another
pool. In those cases the files can even be restored over NFS/CIFS by
using the .zfs/snapshot directory
For example:
http://hub.opensolaris.org/bin/download/User+Group+losug/w%2D2009/Open%2DBackup%2Dwith%2DNotes.pdf
Star implements incremental backups and restores based on POSIX compliant
archives.
ZFS filesystem have functionality beyond POSIX and some of that is
really very important for some people (especially those using CIFS)
Does Star (or any other POSIX archiver) backup:
ZFS ACLs ?
ZFS system attributes (as used by the CIFS server and locally) ?
ZFS dataset properties (compression, checksum etc) ?
If it doesn't then it is providing an "archive" of the data in the
filesystem, not a full/incremental copy of the ZFS dataset. Which
depending on the requirements of the backup may not be enough. In
otherwords you have data/metadata missing from your backup.
The only tool I'm aware of today that provides a copy of the data, and
all of the ZPL metadata and all the ZFS dataset properties is 'zfs send'.
Just like (s)tar alone is not an enterprise backup tool, neither is 'zfs
send'. Both of them need some scripting and infrastructure mangement
around them to make a backup solution suitable for a given deployment.
In some deployments maybe the correct answer is both.
Each have their place (s)tar is a file/directory archiver, 'zfs send' on
the other hand is a ZFS dataset (not just ZPL fileystems since it works
on ZVOLs and all future dataset types too) replication tool that happens
to write out a "stream".
--
Darren J Moffat
_______________________________________________
zfs-discuss mailing list
zfs-discuss@opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
