Date: Wed, 10 Dec 2014 11:40:30 -0800 From: Pete Wright <pete@nomadlogic.org> To: John-Mark Gurney <jmg@funkthat.com> Cc: freebsd-virtualization@freebsd.org Subject: Re: backups of bhyve images Message-ID: <5488A1AE.4090604@nomadlogic.org> In-Reply-To: <20141210192922.GU25139@funkthat.com> References: <20141208163358.GA52969@potato.growveg.org> <33053EB5-91C5-4036-8CC2-34103E33A0FA@mu.org> <CAG=rPVcZc_xs44mXsE%2BPrBsu9CC863HerkvqDQPTxNUEO-V4gQ@mail.gmail.com> <548637D8.1060608@nomadlogic.org> <20141210192922.GU25139@funkthat.com>
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On 12/10/14 11:29, John-Mark Gurney wrote: > Pete Wright wrote this message on Mon, Dec 08, 2014 at 15:44 -0800: >> >> >> On 12/08/14 15:30, Craig Rodrigues wrote: >>> (3) When you want to backup the VM, do a "zfs snapshot" take take a >>> snapshot of the ZFS zvol. >> >> will this ensure that your zvol is consistent, or rather will the >> filesystem overlaid on the zvol device be ensured it is consistent when >> the hypervisor issues a snapshot command? > > That's the beauty of FreeBSD... UFS provides this w/ soft updates, and > ZFS does this through COW... In both cases, as far as I understand it, > it is safe to snapshot the FS... > hrm not sure I think that is a reliable methodology. You'll be forced to recover you VM's filesystem at best, and potentially have corrupt data if blocks were still sitting in cache and had not returned a filehande. My guess is that this method will work with out issues %80-%90 of the time - but you still expose yourself to possible data loss or corruption. I think you and others have mentioned the proper way to do this - snapshot the guess filesystem from with-in the guest VM itself. cheers, -pete -- Pete Wright pete@nomadlogic.org twitter => @nomadlogicLA
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