Re: [Bug-tar] tar vs. zfs

[Joerg Schilling]

Pieter Bowman <address@hidden> wrote:

> This is not a bug per se, but more of an enhancement.
>
> We've been using amanda for many years, using both native dump and GNU
> tar as backup mechanisms.  Recently we started migrating to ZFS on our
> Solaris systems.  One thought I had was to point tar at a ZFS snapshot
> for the purposes of doing backups, giving a stable/read-only
> filesystem for tar to work on.  However, I found a major problem with
> this, in that the device number changes for each snapshot (and is
> different from the parent filesystem).  Since the GNU tar
> listed-incremental option relies on having a consistent device number,
> we're stuck.  I looked through the code and it appears that this
> problem has already been handled when the filesystem is NFS, so as an
> experiment I made the following changes to tar and then made a few
> tests.  The tests seemed to do what I expect them to, but I thought I
> would ask if anybody saw a problem with this.

Similar problems are known for some time.....(even with UFS snapshots).

In case you like to know: star supports the fs-name=/mnt/point for this
reason allowing you to match an existing exntry in /etc/tardumps in case
you use snapshots. 

Jörg

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