hey there,
On Tue, 2009-01-06 at 01:07 +0000, Calum Benson wrote:
> On 17 Dec 2008, at 19:27, Tom Georgoulias wrote:
>
> > Is it safe to assume my options are to either wait for the next
> > release of time-slider or roll my own? Are there any other options?
>
> Well, I guess you could still try using Tim Foster's original ZFS
> Automatic Backup service:
> <http://blogs.sun.com/timf/entry/zfs_automatic_for_the_people
Yeah. That stuff was really aimed at removable USB disks, and never
quite hit the mark [ it assumed FAT32 formatted disks, and send
send-streams as flat files, split into manageable chunks: it was a bit
clunky, and not having a decent "restore" story stopped it in it's
tracks ]
That said, the backup-save-cmd stuff should work ok in the current
shipping version of the automatic snapshot service in 2008.11, it's just
not feature-complete yet. That is, you should be able to send full or
incremental send streams of each snapshot with the right backup-save-cmd
string - some other folks on zfs-discuss@ were doing that successfully
recently.
A more complete solution for dealing with periodic incremental send
streams is a little more complex (and I haven't got cycles to implement
it at the moment unfortunately)
It would involve querying the remote server for a list of snapshots
per dataset we're interested in, then determining which snapshots are
common between the local and remote ends. We could then send an
incremental send stream with differences between that common snapshot,
and the one we've just taken locally.
Right now, as backup-save-cmd is completely freeform, there's no set
protocol to determine how to retrieve that list of remote snapshots, how
to cope with differing levels of snapshots per local dataset[1] etc. so
we just ignore the problem(!). The ZFS Automatic Backup Service did
this properly, checking the USB disk to see whether a full backup stream
was present for each dataset, before choosing to send incrementals,
sending a full backup stream otherwise.
Incidentally, if anyone's interested in working on this support - that'd
be cool, Cc:ing zfs-auto-snapshot in case anyone there has free cycles.
Does that help at all?
cheers,
tim
[1] As the auto-snapshot service allows you to snapshot multiple
unrelated filesystems at a time, any time we add a new local dataset and
choose to also snapshot/backup it, we'd need to ensure that we send
incremental streams for older datasets, and full streams for the new
dataset - gets a bit hairy.
>
> >
>
> I don't know off-hand whether it'll still work on 2008.11 (or if
> they'll be confused by the presence of Time Slider on the same
> machine)-- I suspect it might need a bit of tweaking now. But it
> might at least serve as a decent starting point for your own solution
> until Time Slider supports backups as well as snapshots.
>
> Cheeri,
> Calum.
>
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