Date: Mon, 08 Dec 2014 15:59:32 -0800 From: Peter Grehan <grehan@freebsd.org> To: John <freebsd-lists@potato.growveg.org> Cc: freebsd-virtualization@freebsd.org Subject: Re: backups of bhyve images Message-ID: <54863B64.5010608@freebsd.org> In-Reply-To: <20141208163358.GA52969@potato.growveg.org> References: <20141208163358.GA52969@potato.growveg.org>
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Hi John, > Basically, what I want to do is to run accurate backups without shutting > down and restarting the VM. Is this possible? If it isn't, I think the > only alternative is to make a script that shuts the vm down, copies it, > restarts the vm then runs its compression and backup-over-ssh routine. It's not possible in the general case to take a snapshot of the underlying image since as others have pointed out, it may not be consistent on disk since there are still data/metadata from the guest's filesystem that haven't made it out to disk. Commercial hypervisors provide guest tools that allow a filesystem quiesce/sync that lock-steps with external snapshotting machinery. However, one option that could be worth investigating is using ZFS in the guest with disk images backed by a zvol on the host. ZFS guarantees on-disk consistency, and a zvol provides instantaneous snapshots. Worst case is that some writes are not picked up at snapshot time, but that seems preferable to having to force a full sync in the guest. later, Peter.
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