RE: [Xen-users] Re: FW: Xen Backups

[joost@xxxxxxxxxxxxxxx]

> Wow...nice! This sounds like it would work great for guests that have a
> healthy command line (*NIX) but can you do the same thing on a Windows
> guest?

I'm not sure, as my server doesn't have HVM support.
For a MS Windows guest, I would probably do either of the following 2:
1a) Stop the guest
1b) Create snapshots
1c) start the guest
1d) Create backups
1e) Remove snapshots

or

2a) pause(suspend) the guest (is this possible with HVM?)
2b) create snapshots
2c) copy the pause-file
2d) resume the guest
2e) create backups (Ensure to keep the pause-file with it)
2f) remove snapshots

> I can see connecting to a windows server and then stopping some of the
> services but I am not sure how to mount or unmount a file system in
> windows.

You don't need to actually mount/unmount filesystems as long as you can
ensure there will be no changes made to the filesystem during snapshot
creation.

> Also, forgive my ignorance but, if you had a problem could you just
> reinstall the snapshot and restart it?

What do you mean with reinstalling the snapshot?
If the backup-process fails at any stage, I can resolve it simply by
rebooting the virtual machine. The backups themselves are the actual
filesystems, eg. I can restore this and my system is back.

> Is your script available somewhere or would you mind sharing it?

The script is not yet available somewhere as it's heavily dependent on my
installation and is not yet fit for distribution.

I am planning on documenting it properly this week and will be happy to
make it available.

> PS How about SAN based snapshots (on equipment other than the Netstor)?
> Is this something that people expect Xensource to support in the future?

I have no experience with these, but I would guess that a similar script
would work.

--
Joost

>>
>> On Sunday 01 June 2008 15:33:32 Christian Tramnitz wrote:
>> > I guess most people would like to avoid the necessary downtime.
>> > On the other hand, when doing live-snapshots (i.e. LVM snapshot
> target),
>> > live-data may be corrupt (open file handles, databases)...
>>
>> I actually run a script on the host that does the following:
>> All activities on the guest are done using SSH and shared key
>> authentication
>>
>> 1) Stop the service(s) on the guest
>> 2) Unmount the filesystem(s) on the guest to be backed up
>> 3) detach the filesystems (xm block-detach <domain> <hd??/sd??>)
>> 4) create snapshots
>> 5) reattach the filesystems (xm block-attach <domain> <device>
> <hd??/sd??>
>> w)
>> 6) remount the filesystems on the guest
>> 7) Restart the service(s) on the guest
>>
>> I can then backup the filesystems using the snapshots and remove the
>> snapshots
>> when the backups are finished.
>> Using this, the total 'downtime' is around 40 seconds (on my system)
> to:
>> - stop and start 3 services
>> - backup OpenLDAP and PostgreSQL
>> - unmount / mount 6 filesystems
>> - detach / attach 6 filesystems
>> - create 6 snapshots
>>
>> The script I use also has error-handling implemented in case any
> action
>> fails.
>> This will prevent, for example, a detach-attempt to take place on
> still
>> mounted filesystems.
>>
>> HTH,
>>
>> Joost Roeleveld
>>
>> >
>> > Best regards,
>> >     Christian
>> >
>> > James Alspach wrote:
>> > > How do most people backup their VM's?  I understand that the
> suggested
>> > > method right now is to install your backup client just as you
> would if
>> > > you were backing up a physical server.  It just feels like you
> should
>> be
>> > > able to snapshot the entire VM instead of worrying about just the
>> data.
>> > >
>> > > For instance, how difficult it would be to script taking a VM
> offline,
>> > > exporting it and then bringing it back online.  To me this sounds
> like
>> a
>> > > good way to backup your VM's  (as long as you can stand them being
>> > > offline for some amount of time while they export).  If you could
> back
>> > > up this way recovering from a disaster should be fairly painless.
> Just
>> > > reinstall Xensource, hook it back up to the SAN and import the
>> > > VM's...done.  What am I missing? Is it the size of the VM's that
> keeps
>> > > this from being viable?
>> > >
>> > >
>> > >
>> > > Thanks for your help;
>> > >
>> > > James
>> >
>> > _______________________________________________
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>> > Xen-users@xxxxxxxxxxxxxxxxxxx
>> > http://lists.xensource.com/xen-users
>>
>>
>>
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