----- "Francisco Pérez" fperez.x@gmail.com wrote:
I guess the bad performance it goes with the writing. For example on decompression of a big tar.gz, installing rpm packages. Also on restoring a MySQL Database...
The first clue when i knew that something were wrong was on the FS formating stage. It took really long time to format 40 GB to ext3. I did the same on other machine with a sata disk... surprise! same software and hardware config except for the inferior disk type and did it in no time.
It sounds like your the virtual disk file is sparse. If that's the case, you traded performance for space. It not only has to deal with the underlying filesystem, but it allocates the space on demand and hits that filesystem's journal. Try an LVM logical disk and see how that performs.
LVM on dom0 or domu?
2009/5/20 Christopher G. Stach II cgs@ldsys.net
----- "Francisco Pérez" fperez.x@gmail.com wrote:
I guess the bad performance it goes with the writing. For example on decompression of a big tar.gz, installing rpm packages. Also on restoring a MySQL Database...
The first clue when i knew that something were wrong was on the FS formating stage. It took really long time to format 40 GB to ext3. I did the same on other machine with a sata disk... surprise! same software and hardware config except for the inferior disk type and did it in no time.
It sounds like your the virtual disk file is sparse. If that's the case, you traded performance for space. It not only has to deal with the underlying filesystem, but it allocates the space on demand and hits that filesystem's journal. Try an LVM logical disk and see how that performs.
-- Christopher G. Stach II
CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
In general, disk performance on a domU will always be lower than on a dom0. That being said, I agree with Christopher that is sounds like you are using a sparse disk file.
Did you create this VM with virt-install? If so, you can pass the --nonsparse option to virt-install when creating the VM to allocate all the disk space when creating the VM.
Matt
-- Mathew S. McCarrell Clarkson University '10
mccarrms@gmail.com mccarrms@clarkson.edu
On Wed, May 20, 2009 at 12:35 PM, Francisco Pérez fperez.x@gmail.comwrote:
LVM on dom0 or domu?
2009/5/20 Christopher G. Stach II cgs@ldsys.net
----- "Francisco Pérez" fperez.x@gmail.com wrote:
I guess the bad performance it goes with the writing. For example on decompression of a big tar.gz, installing rpm packages. Also on restoring a MySQL Database...
The first clue when i knew that something were wrong was on the FS formating stage. It took really long time to format 40 GB to ext3. I did the same on other machine with a sata disk... surprise! same software and hardware config except for the inferior disk type and did it in no time.
It sounds like your the virtual disk file is sparse. If that's the case, you traded performance for space. It not only has to deal with the underlying filesystem, but it allocates the space on demand and hits that filesystem's journal. Try an LVM logical disk and see how that performs.
-- Christopher G. Stach II
CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
----- "Francisco Pérez" fperez.x@gmail.com wrote:
LVM on dom0 or domu?
Dom0. After you pvcreate, vgcreate, and lvcreate (or whatever you need to do), use something like this in your VM's config:
disk = [ "phy:/dev/XenVolGroup123/foovm456,xvda,w" ]
If you decide that you prefer the LV setup, you can migrate from your sparse file to a new LV with fdisk, kpartx, and dd.
Thanks all of you. Just with the nonsparse option works all right.
Then an LVM+nonsparse+phy will be the better setup?
Regards.
2009/5/20 Christopher G. Stach II cgs@ldsys.net
----- "Francisco Pérez" fperez.x@gmail.com wrote:
LVM on dom0 or domu?
Dom0. After you pvcreate, vgcreate, and lvcreate (or whatever you need to do), use something like this in your VM's config:
disk = [ "phy:/dev/XenVolGroup123/foovm456,xvda,w" ]
If you decide that you prefer the LV setup, you can migrate from your sparse file to a new LV with fdisk, kpartx, and dd.
-- Christopher G. Stach II
CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
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Christopher G. Stach II -
Francisco Pérez -
Mathew S. McCarrell