[linux-lvm] XFS_freeze and LVM

[Peter Keller]

Hi,

IIRC sometime around 2005 developments in LVM meant that using xfs_freeze 
before creating a snapshot became the wrong thing to do. See the entry in 
the changelog for revision 0.15 of the LVM how-to at 
http://tldp.org/HOWTO/LVM-HOWTO/ . You will probably find that authoritative 
recommendations to use xfs_freeze relate to versions of LVM from before this 
time. (Please correct me if I am wrong about this, someone.)

Also bear in mind that filesystem transactions do not correspond to database 
(i.e. MySQL) transactions. To get a reliable backup using a snapshot you may 
need to allow uncommitted database transactions to complete or roll back 
while preventing new ones from being started, then take the snapshot. Oracle 
has a way of doing this that doesn't need the database to be completely shut 
down, but I have no experience with MySQL so I can't be more specific.

Good luck,
Peter.

On Thu, 27 Nov 2008, Falko Zurell wrote:

> Date: Thu, 27 Nov 2008 09:54:14 +0100
> From: Falko Zurell <falko.zurell at idmedia.com>
> Reply-To: LVM general discussion and development <linux-lvm at redhat.com>
> To: LVM general discussion and development <linux-lvm at redhat.com>
> Subject: Re: [linux-lvm] XFS_freeze and LVM
> 
> Hi,
> are your LVM tools on the freezed file system? Is this the / partition you are
> freezing? Bad idea ;-)
> 
> kind regards
> 
> 
> 
> Am 27.11.2008 um 09:48 schrieb Antony MARTINEAU:
> 
>
>       Hello,
>       I want using LVM 2 and Mysql
>       So i have mounted /var/lib/mysql on /dev/vg0/mysql.
>
>       For doing a backup i want do
>       xfs_freeze -f /var/lib/mysql
>       and after : lvcreate --snapshot -n snap -L1G /dev/vg0/mysql.
>
>       But the problem is when i freeze xfs filesystem i can't use lvm commands...
>       When i unfreeze xfs lvm commands are available...
>
>       Do you know the problem?? is it a bug.??
>       Cordialement,
>
>                                       <ATT54517403.gif>
>
>       MARTINEAU
>       Antony
>       Service informatique
>       Assistant informatique
>       LIPPI Management La Fouillouse
>       16440 Mouthiers sur Boheme
>       Tel.: 05.45.67.34.35
>       Courriel: antony.martineau at lippi.fr
>       http://www.lippi.fr
> 
> 
> 
> 
>
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> Falko Zurell 
> 
> Head of Application Management
> 
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Peter Keller                                     Tel.: +44 (0)1223 353033
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