Date: Thu, 4 Jul 2013 01:13:44 +0100 From: "Steven Hartland" <killing@multiplay.co.uk> To: "Berend de Boer" <berend@pobox.com>, <freebsd-fs@FreeBSD.org> Subject: Re: EBS snapshot backups from a FreeBSD zfs file system: zpool freeze? Message-ID: <BD8B4240539A46FC9FB86615A7F675CA@multiplay.co.uk> References: <87li5o5tz2.wl%berend@pobox.com>
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----- Original Message ----- From: "Berend de Boer" <berend@pobox.com> > Hi All, > > I'm experimenting with building a FreeBSD NFS server on Amazon AWS > EC2. I've created a zpool with 5 disks in a raidz2 configuration. > > How can I make a consistent backup of this using EBS? > > On Linux' file systems I can freeze a file system, start the backup of > all disks, and unfreeze. This freeze usually only takes 100ms or so. > > ZFS on FreeBSD does not appear to have such an option. I.e. what I'm > looking for is basically a hardware based snapshot. ZFS should simply > be suspended at a recoverable point for a few hundred ms. > > A similar question from 2010 is here: > http://thr3ads.net/zfs-discuss/2010/11/580781-how-to-quiesce-and-unquiesc-zfs-and-zpool-for-array-hardware-snapshots > > Absent a "zfs freeze" it seems using FreeBSD/zfs on AWS with EBS is > going to be impossible. Unfortunately that means back to Linux sigh. Not been following the thread really so excuse if this has already been mentioned ;-) There is a zpool freeze <pool> which stops spa_sync() from doing anything, so that the only way to record changes is on the ZIL. The comment in the zpool_main is: "'freeze' is a vile debugging abomination" so it's evil but might be what you want if you're up to writing some code. For more info have a look at ztest. Regards Steve ================================================ This e.mail is private and confidential between Multiplay (UK) Ltd. and the person or entity to whom it is addressed. In the event of misdirection, the recipient is prohibited from using, copying, printing or otherwise disseminating it or any information contained in it. In the event of misdirection, illegible or incomplete transmission please telephone +44 845 868 1337 or return the E.mail to postmaster@multiplay.co.uk.
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