Darren J Moffat wrote:
Is there a reason why you can't just walk through the snapshot using
POSIX APIs ? The snapshot is mounted in
<rootofdataset>/.zfs/snapshot/<nameofsnapshot>
We cannot walk through the mounted snapshot as it's not just the data
that we are concerned about. We need to read the complete snapshot
(data+metadata).
Or maybe zfs send/recv is what you need.
I looked at zfs send/recv and was pleasantly surprised by its
capabilities. Unfortunately it does not fit into our backup agent's
design (NDMP based). The agent
reads directly of a snapshot - using zfs send would require additional
space to create the backup file. (and we cannot do a zfs send to the
destination, even
though it would have been nice :) ).
Given that you can't read the filesystem as a block device in the
first place why would it make sense to do so for a snapshot of
filesystem ?
I know it doesn't make much sense, I was just hoping that zfs's
snapshots could be used by a different product/vendor.
Sure they can but I'm not sure you are approaching the problem from a
view that ZFS can give you on the data.
It might help if you described how this backup software works for
other filesystems, eg UFS.
For UFS (as with other filesystems eg. NTFS) - we use the filesystem's
local snapshot mechanism (fssnap/vss). In all cases you can refer to the
snapshot as a block device.
Thanks,
mnh
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