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List: linux-lvm
Subject: [linux-lvm] Re: Re: Loopback mount a disk image with lvm (Girish)
From: "Girish V" <girish.xen () gmail ! com>
Date: 2008-06-09 12:58:17
Message-ID: 2122f0920806090558j180263f8uadd209c608220e84 () mail ! gmail ! com
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Thanks Dave,
This worked like a charm.
Girish
On Mon, Jun 9, 2008 at 6:10 AM, <linux-lvm-request@redhat.com> wrote:
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> Today's Topics:
>
> 1. striping question (Mag Gam)
> 2. Loopback mount a disk image with lvm (Girish V)
> 3. Re: Loopback mount a disk image with lvm (David Robinson)
> 4. Re: Performance tunning on LVM2 (Heinz Mauelshagen)
> 5. Re: Performance tunning on LVM2 (Antony MARTINEAU)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sat, 7 Jun 2008 11:39:09 -0400
> From: "Mag Gam" <magawake@gmail.com>
> Subject: [linux-lvm] striping question
> To: linux-lvm@redhat.com
> Message-ID:
> <1cbd6f830806070839l436b0b4ai99d3c4264e896ea6@mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> If I am using x RAID 5 volumes and create PVs. Once I create the LVs is it a
> good idea to stripe them? If so, what is a valid stripe size?
>
> I am looking for performance BTW.
>
>
> TIA
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> ------------------------------
>
> Message: 2
> Date: Sun, 8 Jun 2008 18:23:23 -0400
> From: "Girish V" <girish.xen@gmail.com>
> Subject: [linux-lvm] Loopback mount a disk image with lvm
> To: linux-lvm@redhat.com
> Message-ID:
> <2122f0920806081523w7a7ce274q9707992948f6e1b4@mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> Hello,
>
> I have a disk.img (a disk image file, raw format) with the following "fdisk -l"
>
> Device Boot Start End Blocks Id System
> disk.img1 * 1 13 104391 83 Linux
> disk.img2 14 2491 19904535 8e Linux LVM
>
> Now I can loopback mount the first bartition using
> "mount -o loop,offset=32256 disk.img /mnt".
>
> I need to mount the second partition. If the secoond partition had
> been an ext3 partition, I would have loopback mounted it as
> "mount -o loop,offset=$((255*63*512*13) disk.img /mnt", but when I try
> that, I get
> mount: unknown filesystem type 'LVM2_member'
>
> Any help is greatly appreciated.
>
> Thanks.
>
>
>
> ------------------------------
>
> Message: 3
> Date: Mon, 9 Jun 2008 10:52:54 +1000
> From: "David Robinson" <zxvdr.au@gmail.com>
> Subject: Re: [linux-lvm] Loopback mount a disk image with lvm
> To: "LVM general discussion and development" <linux-lvm@redhat.com>
> Message-ID:
> <b072968d0806081752s79f32e66h4c6d7de1b42094a0@mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> On Mon, Jun 9, 2008 at 8:23 AM, Girish V <girish.xen@gmail.com> wrote:
> > Hello,
> >
> > I have a disk.img (a disk image file, raw format) with the following "fdisk -l"
> >
> > Device Boot Start End Blocks Id System
> > disk.img1 * 1 13 104391 83 Linux
> > disk.img2 14 2491 19904535 8e Linux LVM
> >
> > Now I can loopback mount the first bartition using
> > "mount -o loop,offset=32256 disk.img /mnt".
> >
> > I need to mount the second partition. If the secoond partition had
> > been an ext3 partition, I would have loopback mounted it as
> > "mount -o loop,offset=$((255*63*512*13) disk.img /mnt", but when I try
> > that, I get
> > mount: unknown filesystem type 'LVM2_member'
> >
> > Any help is greatly appreciated.
>
> losetup /dev/loop0 disk.img
> kpartx -a /dev/loop0
>
> Then to mount the first partition:
>
> mount /dev/mapper/loop0p1 /mnt
>
> Or to activate the volume group then mount the logical volume:
>
> vgscan
> vgchange -ay vg
> mount /dev/vg/lv /mnt
>
> Hope that helps.
>
> --Dave
>
>
>
> ------------------------------
>
> Message: 4
> Date: Mon, 9 Jun 2008 11:44:53 +0200
> From: Heinz Mauelshagen <mauelshagen@redhat.com>
> Subject: Re: [linux-lvm] Performance tunning on LVM2
> To: LVM general discussion and development <linux-lvm@redhat.com>
> Message-ID: <20080609094453.GA5507@redhat.com>
> Content-Type: text/plain; charset=us-ascii
>
> On Fri, Jun 06, 2008 at 08:03:51AM -0700, Larry Dickson wrote:
> > A (linear) volume group made of two physical volumes consists of one PV
> > followed by the other, rather like a "Raid-Linear". If you size the
> > origin logical volume right, you can get one LV (the origin) to fall on one
> > disk, and force the snapshot to land on the other disk. This eliminates
> > back-and-forth seeking to the COW. Whether it solves your problem will
> > depend on how smart the driver is about the read-before-write activity on
> > the origin volume.
> >
> > Other members of the list may have more experience on this. Comments?
>
> If I read correctly, Antony just has *ONE* PV.
>
> So no matter what, he has to add another to allow for snapshot COW
> store allocation on that other PV, distinct from the one holding
> the origin(s). Presumably there's no other bottleneck aside from the
> disk, that'll do better.
>
> Keep in mind, that unless you've got streaming writes, the performance
> won't drop as much as in the (artificial) dd test below.
>
> FYI: With the current snapshot implementation, multiple snapshots per single
> origin will throttle write performance because of write duplication
> to all per snapshot COW stores.
>
> Heinz
>
> >
> > Larry
> >
> > On 6/6/08, Antony MARTINEAU <Antony.MARTINEAU@lippi.fr> wrote:
> > >
> > >
> > > The volume group vg0 is the raid0 of two disk (SAS 15000rpm 300G0)
> > > I have only this raid on the server
> > >
> > > But i don't understand, imagine i make a volume group ou of this raid0. It
> > > is no possible to snapshot the original volume, am i wrong?
> > >
> > > If i make a new VG on another disks, For exemple /dev/vg1/
> > > LVM don't permit to store a snaphot on a different VG than the origin
> > > volum.
> > >
> > > for exemple /dev/vg0/test cant be snapshoting on /dev/vg1/test.snap
> > >
> > > LV test and LV test.snap must be on the same volume, am i wrong ???? so it
> > > is impossible to store snapshot on another disk....
> > >
> > >
> > > Cordialement,
> > >
> > > *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* <antony.martineau@lippi.fr>*
> > > **http://www.lippi.fr* <http://www.lippi.fr/>
> > >
> > >
> > >
> > > De : "Larry Dickson" <ldickson@cuttedge.com> Pour : "LVM general
> > > discussion and development" <linux-lvm@redhat.com> Date: 06/06/2008 16:19 Objet
> > > > Re: [linux-lvm] Performance tunning on LVM2
> > > ------------------------------
> > >
> > >
> > >
> > > This looks like the result of excessive seeking. Are origin volume and
> > > snapshot both on the same physical drive? Is it possible to make a volume
> > > group out of two drives, and arrange things so that origin volume and
> > > snapshot are hitting different disks?
> > >
> > > Larry Dickson
> > > Cutting Edge Networked Storage
> > >
> > > On 6/6/08, *Antony MARTINEAU* \
> > > <*Antony.MARTINEAU@lippi.fr*<Antony.MARTINEAU@lippi.fr>> wrote:
> > >
> > > Hello,
> > > My configuration:
> > > Server DELL 2860 Intel(R) Xeon(R) CPU X3230 @ 2.66GHz (Quad Core)
> > > 8GB of memory
> > > 2 x SAS 15000 300G0 RAID 0 hardware
> > > SLES 10 SP2
> > > Kernel 2.6.16.60-0.21-xen
> > >
> > > i have one volume group vg0 ( whith one PV, the two disks in raid0) whith
> > > many lvm
> > > I am very surprise about LVM2 performance when a snapshot is done.
> > > Write speed on the Original volume is very bad when a snaphot is active...
> > >
> > > For exemple:
> > > *
> > > Speed on /dev/vg0/test when there is NO snapshot :*
> > >
> > > suse2:~ # dd if=/dev/zero of=/dev/vg0/test bs=2M count=400
> > > 400+0 records in
> > > 400+0 records out
> > > 838860800 bytes (839 MB) copied, 6.42741 seconds, 131 MB/s
> > > *
> > > Speed on /dev/vg0/test when there is one snapshot of this original volume :
> > > *
> > >
> > > suse2:~ # lvremove --force /dev/vg0/test3.snap
> > > Logical volume "test3.snap" successfully removed
> > > suse2:~ # dd if=/dev/zero of=/dev/vg0/test bs=2M count=400
> > > 400+0 records in
> > > 400+0 records out
> > > 838860800 bytes (839 MB) copied, 6.42741 seconds, 131 MB/s
> > > suse2:~ # lvcreate -s -L1G -ntest.snap /dev/vg0/test
> > > Logical volume "test.snap" created
> > > suse2:~ # dd if=/dev/zero of=/dev/vg0/test bs=2M count=400
> > > 400+0 records in
> > > 400+0 records out
> > > 838860800 bytes (839 MB) copied, 204.862 seconds, 4.1 MB/s
> > >
> > > *
> > > Speed on /dev/vg0/test when there is 2 snapshots of this original volume :
> > > *
> > >
> > > suse2:~ # lvcreate -s -L1G -ntest1.snap /dev/vg0/test
> > > Logical volume "test1.snap" created
> > > suse2:~ # lvcreate -s -L1G -ntest2.snap /dev/vg0/test
> > > Logical volume "test2.snap" created
> > > suse2:~ # lvremove /dev/vg0/test2.snap
> > > Do you really want to remove active logical volume "test2.snap"? [y/n]: y
> > > Logical volume "test2.snap" successfully removed
> > > suse2:~ # dd if=/dev/zero of=/dev/vg0/test bs=2M count=400
> > > 400+0 records in
> > > 400+0 records out
> > > 838860800 bytes (839 MB) copied, 270.928 seconds, 3.1 MB/s
> > >
> > >
> > > Do you know some elements about tunning performance?,?
> > >
> > > Performances are disastrous when a snaphot is active
> > > Could you give your speed result? and your amelioration??
> > >
> > > ps:Results are the same whithout Kernel Xen and whith a kernel more recent
> > > (*2.6.24.2* <http://2.6.24.2/>) Cordialement,
> > > *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* <antony.martineau@lippi.fr>*
> > > **http://www.lippi.fr* <http://www.lippi.fr/>
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
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> > >
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> > >
> > >
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> > > **https://www.redhat.com/mailman/listinfo/linux-lvm*<https://www.redhat.com/mailman/listinfo/linux-lvm>
> > > read the LVM HOW-TO at \
> > > *http://tldp.org/HOWTO/LVM-HOWTO/*<http://tldp.org/HOWTO/LVM-HOWTO/> \
> > > _______________________________________________ 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/
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > Ce message et toutes les pieces jointes sont etablis a l'attention
> > > exclusive de ses destinataires et sont strictement confidentiels. *Pour en
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> > >
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> > >
> > >
> > > _______________________________________________
> > > linux-lvm mailing list
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> > > https://www.redhat.com/mailman/listinfo/linux-lvm
> > > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
> > >
>
>
>
>
> > _______________________________________________
> > 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/
>
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>
> Heinz Mauelshagen Red Hat GmbH
> Consulting Development Engineer Am Sonnenhang 11
> Storage Development 56242 Marienrachdorf
> Germany
> Mauelshagen@RedHat.com PHONE +49 171 7803392
> FAX +49 2626 924446
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>
>
>
> ------------------------------
>
> Message: 5
> Date: Mon, 9 Jun 2008 12:06:19 +0200
> From: Antony MARTINEAU <Antony.MARTINEAU@lippi.fr>
> Subject: Re: [linux-lvm] Performance tunning on LVM2
> To: mauelshagen@redhat.com, LVM general discussion and development
> <linux-lvm@redhat.com>
> Message-ID:
> <OF8D53F89C.8A8CDA30-ONC1257463.00362B8A-C1257463.00377B47@lippi.fr>
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