Re: [Bug-tar] Problem with gnu tar and ZFS on Linux

[Joerg Schilling]

Pieter Bowman <address@hidden> wrote:

> We have been using gnu tar with amanda to backup our ZFS filesystems
> on Solaris (both SPARC and x86) for more than 10 years.  We take a ZFS

Did you ever run a restore operation?

> snapshot (destroying the previous snapshot if it exists), run amanda
> pointing to the snapshot directory.  We are in the process of
> replacing our old Solaris x86 file server with one running CentOS and
> ZFS.  Unfortunately, that project has now stalled because the same
> process that we've been using no longer works.  Every night we end up
> backing up the full filesystem (only three at the moment, but that's
> still hundreds of gigabytes).  I did add the --no-check-device switch,
> but that didn't help.

If the problem is that the stat.st_dev entry of the stat() data differs from
one snapshot to another, I see no problems if you use star(1) for incremental 
backups.

The FreeBSD people use star(1) for incremental ZFS backps since the beginning 
of the ZFS port to FreeBSD.

star only remembers the time stamp of the last and the current incremental and 
decides what to do just based on inode numbers. So in fact star uses the basic 
concept from ufsdump/ufsrestore to find which files have been renamed and which 
files have been removed.

BTW: We did run a daily dump/restore pipeline for 10 years on a larger server 
in order to create a mirrored filesystem and there never has been any problem.

I recommend to use the star source from the latest schilytools.


Jörg

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