RE: [Xen-users] Backup solution

["Artur Linhart - Linux communication" <AL.LINUX@xxxxxxxxxxx>]

Hello,

        I§ve thought about it and i think the good compromise seems to be
for me

1. start "xm save" to archieve the current and consistent state of the
memory
2. during the "xm save" command is running , the domain is paused, I can
create the snapshot volume during this time (in script could be waited till
the saved memory snapshot file will be created on the disk, if I understand
it correctly, at this moment the domain must be already paused, so now the
snapshot can be created
3. after the save is executed, the xm restore can be done again (or the
command "xm save" can be started with the option -c to leave the domain
running after the memory snapshot will be created, but this can be dangerous
in the case the "xm save" would take too less time to create the snapshot
volume during this time)

The virtual machine state will be backed up as the memory snapshot plus the
snapshot partition - if I have both of them, I can every time restore by "xm
restore" the old state of the virtual machine - and from my point of view,
it should be consistent. 
Or I am wrong?
The run of the virtual server is in this case interrupted only for the time
the memory snapshot is created - so, this can be something like seconds, or
half a minute.
I think, at least I, because I deal with no space-shuttle rutime control and
management system :-), I can good live with 20 seconds unavailability of the
server...

        With regards

                Archie

-----Original Message-----
From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Nico
Kadel-Garcia
Sent: Tuesday, July 10, 2007 7:24 PM
To: Artur Linhart
Cc: 'xen-users'; 'Fajar A. Nugraha'
Subject: Re: [Xen-users] Backup solution

Artur Linhart wrote:
> OK, but - if You create the LVM snapshot volume and make the backup of it,
> You assume the OS running in VM has written everything correctly to the
> logical volume and the logical volume is in consistent state. 
> But this assumption seems to be dangerous for me, especially by Windows
DomU
> - how can You be sure, the OS hdd driver has written everything to the
> logical volume before You create the snapshot volume?
>
> I would like also to use the LVM snapshots for backup, but this topic is a
> problem for me, which I could not solve yet...
>
>       With regards
>
>               Archie
>   
Windows snapshot backups are a serious, serious problem. Complex 
software plays enormously complex games to provide this.

Frankly, the most reliable is to actually shut down the machine, *then* 
take an LVM snapshot, then reboot it to keep service active wile using 
the LVM snapshot for backup. Not pause: not suspend: *halt* the thing.

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