[linux-lvm] Loopback mount a disk image with lvm

Discussion:

Girish V

2008-06-08 22:23:23 UTC

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.

David Robinson

2008-06-09 00:52:54 UTC

Permalink

Post by Girish V
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

Girish V

2008-06-09 13:46:29 UTC

Permalink

Incidentally, how do I free the loop (/dev/loop0) associated with
disk.img. I tried "sudo losetup -d /dev/loop0", but I get the error
message "ioctl: LOOP_CLR_FD: Device or resource busy".

I tried looking at mount, ps, top etc - but the disk.img associated
with loop0, was not being used.

Any ideas?
Thanks

Thanks for your answer...
But my test show that it is, the LVM2 software the probleme...

device-mapper snapshot target actually.

Because even whith 3 writing test at the same time on 3 LV which are on
the same VG and the same PV, the performance are better than one LV whith
only one snapshot...

Sure, the write patterns for snapshots go sequentially to the disk
(i.e. read from origin, write to COW store, write to origin, ...).

suse2:~ # dd if=/dev/zero of=/dev/vg0/test bs=10M count=150
150+0 records in
150+0 records out
1572864000 bytes (1.6 GB) copied, 27.9422 seconds, 56.3 MB/s
suse2:~ # dd if=/dev/zero of=/dev/vg0/test2 bs=10M count=150
150+0 records in
150+0 records out
1572864000 bytes (1.6 GB) copied, 33.2836 seconds, 47.3 MB/s
suse2:~ # dd if=/dev/zero of=/dev/vg0/test3 bs=10M count=150
150+0 records in
150+0 records out
1572864000 bytes (1.6 GB) copied, 33.784 seconds, 46.6 MB/s
With 3 writing test AT THE SAME TIME , the average is better that one
writing test on one LV whith one snap
Look,
suse2:~ # lvcreate -s -L2G -ntest.snap /dev/vg0/test
Logical volume "test.snap" created
suse2:~ # dd if=/dev/zero of=/dev/vg0/test bs=10M count=150
150+0 records in
150+0 records out
1572864000 bytes (1.6 GB) copied, 382.315 seconds, 4.1 MB/s
It is disastrous...
I think dd is a good test...

It's an extreme test like I tried to point out.
Like already mentioned: you gotta put the COW store on a seperate PV
after adding one to your vg0 (say /dev/sdb1).
pvcreate /dev/sdb1
vgextend vg0 /dev/sdb1
lvcreate -s -L2G -ntest.snap /dev/vg0/test /dev/sdb1
Heinz

Cordialement,
MARTINEAU
Antony
Service informatique
Assistant informatique
LIPPI Management
La Fouillouse
16440 Mouthiers sur Boheme
Tel.: 05.45.67.34.35
http://www.lippi.fr
09/06/2008 11:46
Re: [linux-lvm] Performance tunning on LVM2

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

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

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
**http://www.lippi.fr* <http://www.lippi.fr/>

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*
Hello,
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...

*
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
*
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
*
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
**http://www.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* <http://www.lippi.fr/disclaimer.php>
This message and any attachments are confidential to the ordinary user

the e-mail address to which it was addressed and may also be

privileged. *More

information* <http://www.lippi.fr/disclaimer.php>
_______________________________________________
linux-lvm mailing list*
**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
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

savoir plus cliquer ici* <http://www.lippi.fr/disclaimer.php>
This message and any attachments are confidential to the ordinary user

the e-mail address to which it was addressed and may also be

privileged. *More

information* <http://www.lippi.fr/disclaimer.php>
_______________________________________________
linux-lvm mailing list
https://www.redhat.com/mailman/listinfo/linux-lvm
read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

_______________________________________________
linux-lvm mailing list
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
FAX +49 2626 924446
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
_______________________________________________
linux-lvm mailing list
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
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

Send linux-lvm mailing list submissions to
To subscribe or unsubscribe via the World Wide Web, visit
https://www.redhat.com/mailman/listinfo/linux-lvm
or, via email, send a message with subject or body 'help' to
You can reach the person managing the list at
When replying, please edit your Subject line so it is more specific
than "Re: Contents of linux-lvm digest..."
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
Subject: [linux-lvm] striping question
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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://www.redhat.com/archives/linux-lvm/attachments/20080607/69fbc84c/attachment.html
------------------------------
Message: 2
Date: Sun, 8 Jun 2008 18:23:23 -0400
Subject: [linux-lvm] Loopback mount a disk image with lvm
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
Subject: Re: [linux-lvm] Loopback mount a disk image with lvm
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.

losetup /dev/loop0 disk.img
kpartx -a /dev/loop0
mount /dev/mapper/loop0p1 /mnt
vgscan
vgchange -ay vg
mount /dev/vg/lv /mnt
Hope that helps.
--Dave
------------------------------
Message: 4
Date: Mon, 9 Jun 2008 11:44:53 +0200
Subject: Re: [linux-lvm] Performance tunning on LVM2
Content-Type: text/plain; charset=us-ascii

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

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
**http://www.lippi.fr* <http://www.lippi.fr/>
: 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
Hello,
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...
*
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
*
*
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
*
*
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
**http://www.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* <http://www.lippi.fr/disclaimer.php>
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* <http://www.lippi.fr/disclaimer.php>
_______________________________________________
linux-lvm mailing list*
**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
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
savoir plus cliquer ici* <http://www.lippi.fr/disclaimer.php>
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* <http://www.lippi.fr/disclaimer.php>
_______________________________________________
linux-lvm mailing list
https://www.redhat.com/mailman/listinfo/linux-lvm
read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

_______________________________________________
linux-lvm mailing list
https://www.redhat.com/mailman/listinfo/linux-lvm
read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

------------------------------
_______________________________________________
linux-lvm mailing list
https://www.redhat.com/mailman/listinfo/linux-lvm
End of linux-lvm Digest, Vol 52, Issue 9
****************************************

Bryn M. Reeves

2008-06-09 13:51:33 UTC

Permalink

Post by Girish V
Incidentally, how do I free the loop (/dev/loop0) associated with
disk.img. I tried "sudo losetup -d /dev/loop0", but I get the error
message "ioctl: LOOP_CLR_FD: Device or resource busy".
I tried looking at mount, ps, top etc - but the disk.img associated
with loop0, was not being used.

Unmount all the file systems, deactivate the VG with "vgchange -an
<vgname>" (if you mounted/activated them) and finally delete the kpartx
mappings with "kpartx -d /dev/loop0". That should release all references
on the loop devices allowing you to unbind it with losetup.

Regards,
Bryn.

Milan Broz

2008-06-09 13:51:48 UTC

Permalink

kpartx -d /dev/loop0

to remove partitions mappings?

Milan

Girish V

2008-06-09 15:19:53 UTC

Permalink

I figured out that I had to do the following before I could free the loop device

vgchange -an VolGroup00
kpartx -d /dev/loop0
losetup -d /dev/loop0

Girish

Thanks for your answer...
But my test show that it is, the LVM2 software the probleme...

device-mapper snapshot target actually.

Because even whith 3 writing test at the same time on 3 LV which are on
the same VG and the same PV, the performance are better than one LV whith
only one snapshot...

Sure, the write patterns for snapshots go sequentially to the disk
(i.e. read from origin, write to COW store, write to origin, ...).

one

the origin volume.
Other members of the list may have more experience on this. Comments?

Larry

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

so it

16:19 Objet

volume

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...

[y/n]: y

recent

*Pour en

savoir plus cliquer ici* <http://www.lippi.fr/disclaimer.php>
This message and any attachments are confidential to the ordinary user

the e-mail address to which it was addressed and may also be

privileged. *More

information* <http://www.lippi.fr/disclaimer.php>
_______________________________________________
linux-lvm mailing list*
**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/>

*Pour en

savoir plus cliquer ici* <http://www.lippi.fr/disclaimer.php>
This message and any attachments are confidential to the ordinary user

the e-mail address to which it was addressed and may also be

privileged. *More

_______________________________________________
linux-lvm mailing list
https://www.redhat.com/mailman/listinfo/linux-lvm
read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

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.

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

_______________________________________________
linux-lvm mailing list
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
FAX +49 2626 924446
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
------------------------------
Message: 5
Date: Mon, 9 Jun 2008 12:06:19 +0200
Subject: Re: [linux-lvm] Performance tunning on LVM2
Content-Type: text/plain; charset="us-ascii"
Skipped content of type multipart/alternative-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: image/gif
Size: 5552 bytes
Desc: not available
Url : https://www.redhat.com/archives/linux-lvm/attachments/20080609/c6399248/attachment.gif
------------------------------
_______________________________________________
linux-lvm mailing list
https://www.redhat.com/mailman/listinfo/linux-lvm
End of linux-lvm Digest, Vol 52, Issue 9
****************************************