Hello Lars,
Andreas was whith us the last week ;-)
So I think to that xfs_freeze is no needed during a snapshot LVM2
My backup Script do :
FLUSH TABLES WITH READ LOCK;
system lvcreate --snapshot -n $snapname -L$snapsize /dev/$vg/$lv;
UNLOCK TABLES;
So i think it is the best way to backup
The last message about peter Keller worring me... You think to that XFS is not a filesystem that correspond whit database transactions???
I think XFS is actually the best FS on all domains... can i use XFS for mysql database??
| De : | linux-lvm-request@redhat.com |
| A: | linux-lvm@redhat.com |
| Date: | 28/11/2008 16:40 |
| Objet : | linux-lvm Digest, Vol 57, Issue 15 |
| Envoyé par : | linux-lvm-bounces@redhat.com |
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Today's Topics:
1. XFS_freeze and LVM (Antony MARTINEAU)
2. Re: XFS_freeze and LVM (Falko Zurell)
3. Re: XFS_freeze and LVM (Peter Keller)
4. Re: XFS_freeze and LVM (Lars Ellenberg)
----------------------------------------------------------------------
Message: 1
Date: Thu, 27 Nov 2008 09:48:12 +0100
From: Antony MARTINEAU <Antony.MARTINEAU@lippi.fr>
Subject: [linux-lvm] XFS_freeze and LVM
To: linux-lvm@redhat.com
Message-ID:
<OFEEAC56CA.4D4B448B-ONC125750E.00300773-C125750E.00305B8E@lippi.fr>
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Message: 2
Date: Thu, 27 Nov 2008 09:54:14 +0100
From: Falko Zurell <falko.zurell@idmedia.com>
Subject: Re: [linux-lvm] XFS_freeze and LVM
To: "LVM general discussion and development" <linux-lvm@redhat.com>
Message-ID: <E3E8DACD-916F-4A20-AE40-535AE1373326@idmedia.com>
Content-Type: text/plain; charset="utf-8"
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@lippi.fr
> http://www.lippi.fr
>
>
>
>
>
>
>
>
>
> Ce message et toutes les pieces jointes sont etablis a l'attention
> exclusive de ses destinataires et sont strictement confidentiels.
> Pour en savoir plus cliquer ici
>
> This message and any attachments are confidential to the ordinary
> user of the e-mail address to which it was addressed and may also be
> privileged. More information
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
Falko Zurell 
Head of Application Management
/i-d media AG
Ohlauer Straße 43
D-10999 Berlin
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Message: 3
Date: Thu, 27 Nov 2008 10:28:05 +0000 (GMT)
From: Peter Keller <pkeller@globalphasing.com>
Subject: Re: [linux-lvm] XFS_freeze and LVM
To: LVM general discussion and development <linux-lvm@redhat.com>
Message-ID:
<alpine.LNX.1.10.0811271006200.27683@bernoulli.globalphasing.com>
Content-Type: text/plain; charset="utf-8"
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@idmedia.com>
> Reply-To: LVM general discussion and development <linux-lvm@redhat.com>
> To: LVM general discussion and development <linux-lvm@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@lippi.fr
> http://www.lippi.fr
>
>
>
>
>
> [eco.jpg]
>
>
> Ce message et toutes les pieces jointes sont etablis a l'attention
> exclusive de ses destinataires et sont strictement confidentiels. Pour en
> savoir plus cliquer ici
>
> This message and any attachments are confidential to the ordinary user of
> the e-mail address to which it was addressed and may also be privileged.
> More information
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>
>
> Falko Zurell 
>
> Head of Application Management
>
> /i-d media AG
> Ohlauer Straße 43
> D-10999 Berlin
>
>
>
>
>
--
Peter Keller Tel.: +44 (0)1223 353033
Global Phasing Ltd., Fax.: +44 (0)1223 366889
Sheraton House,
Castle Park,
Cambridge CB3 0AX
United Kingdom
------------------------------
Message: 4
Date: Fri, 28 Nov 2008 16:39:40 +0100
From: Lars Ellenberg <lars.ellenberg@linbit.com>
Subject: Re: [linux-lvm] XFS_freeze and LVM
To: linux-lvm@redhat.com
Message-ID: <20081128153940.GI18698@barkeeper1-xen.linbit>
Content-Type: text/plain; charset=iso-8859-1
On Thu, Nov 27, 2008 at 10:28:05AM +0000, Peter Keller wrote:
> 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.
at some stage lvm/devicemapper started to do the freeze implicitly
(on file systems that support freeze), and somewhen in between I think
there was a deadlock on "double freeze" (some long time ago).
maybe that is what you see.
on "modern" systems, it should work either way, with or without the
explicit freeze (as long as you don't try to freeze your root fs,
probably).
for mysql and (innodb) transaction safety, yes,
it is enough to use (writeable) snapshots.
however, iirc, you better do a "FLUSH TABLES WITH READ LOCK" (which may
take a long time, as it waits for all pending statements to complete),
then create the snapshot (which implicitly also freezes/unfreezes the
fs), and "UNLOCK TABLES" again.
--
: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com
DRBD® and LINBIT® are registered trademarks of LINBIT, Austria.
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