Disk cloning

[Brett Delle Grazie]

Hi,

LVM snapshots are fine with MySQL, please check the MySQL manual under backups for your particular
MySQL version.

Difficulties arise when using INNODB storage as the database _must_ be shutdown long enough to take the snapshot.  Otherwise your only solution for a consistent backup is to use the commercial innobackup tool.

Best regards,

Brett

-----Original Message-----
From: Ryan Bair [mailto:ryandbair at gmail.com] 
Sent: Wednesday, January 21, 2009 1:11 PM
To: linux-poweredge at dell.com
Subject: Re: Disk cloning

It's supposed to sync before the snapshot, yes. The whole idea is that the snapshot is consistent with the disk at the point in time the snapshot was taken which makes it leaps and bounds better than just running dd/rsync/tar on the raw volume. Consistent backups are the only reason LVM has snapshots as the current implementation is pretty useless for anything else.

To the database it will be just like if you pulled the plug at that exact moment that you took the snapshot. Any database worth using _will_ be able to recover and continue on its merry way when you start up from the backup. Not so sure about MySQL though. :-)

--Ryan

On Wed, Jan 21, 2009 at 4:55 AM, Tino Schwarze <linux-poweredge.lists at tisc.de> wrote:
> Hi,
>
> On Tue, Jan 20, 2009 at 04:35:37PM -0500, Ryan Bair wrote:
>
>> Are your active volumes on LVM? If so an LVM snapshot will make this 
>> much easier. (Didn't see this mentioned yet, but it is a huge thread)
>
> An LVM snapshot is probably only slightly better than dd. It won't 
> give you a consistent database storage either. It might do a sync on 
> the file systems but I'm not sure.
>
> Tino.
>
> --
> "What we nourish flourishes." - "Was wir nähren erblüht."
>
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