Date: Mon, 08 Jul 2013 09:53:28 +1200 From: Berend de Boer <berend@pobox.com> To: Markus Gebert <markus.gebert@hostpoint.ch> Cc: freebsd-fs <freebsd-fs@freebsd.org> Subject: Re: EBS snapshot backups from a FreeBSD zfs file system: zpool freeze? Message-ID: <87zjty11gn.wl%berend@pobox.com> In-Reply-To: <14A2336A-969C-4A13-9EFA-C0C42A12039F@hostpoint.ch> References: <87li5o5tz2.wl%berend@pobox.com> <CA%2BtpaK1jQuKneQsxkVfxJGzXdPdLZfqBM1QWQ0e19nK5t71t1Q@mail.gmail.com> <87ehbg5raq.wl%berend@pobox.com> <20130703055047.GA54853@icarus.home.lan> <6488DECC-2455-4E92-B432-C39490D18484@dragondata.com> <CADBaqmihCB5JP01hLwXTWHoZiJJ5-jkT-Ro=oDwOcKZT_zvEKA@mail.gmail.com> <A5A66641-5EF9-454E-A767-009480EE404E@dragondata.com> <14A2336A-969C-4A13-9EFA-C0C42A12039F@hostpoint.ch>
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>>>>> "Markus" == Markus Gebert <markus.gebert@hostpoint.ch> writes:
Markus> But taking a zfs snapshot is an atomic operation. Why not
Markus> use that? For example:
Markus> 1. snapshot the zfs at the same point in time you'd issue
Markus> that ioctl on Linux 2. take the EBS snapshot at any time
Markus> 3. clone the EBS snapshot to the new/other VM 4. zfs
Markus> import the pool there 5. zfs rollback the filesystem to
Markus> the snapshot taken in step 1 (or clone it and use that)
OK, various tests later: this does not really work. If you create the
snapshot, and make a backup, the snapshot does not show up on the
backup (whatever the reason, perhaps the disks so inconsistent zfs has
to rollback).
But the biggest issue is that if writing is going on and you make the
EBS snapshot, you can't really mount it. Maybe zfs mounts after hours,
but I just gave if it didn't mount it after 1.5 hours.
Another interesting thing I've seen was a completely empty drive after
mount!
So clearly EBS snapshots on a mounted multi-drive pool don't work.
--
All the best,
Berend de Boer
------------------------------------------------------
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