Re: [CentOS-virt] Bad Disk Performance of domU
- "Francisco Pérez" wrote: > Thanks all of you. Just with the nonsparse option works all right. > > Then an LVM+nonsparse+phy will be the better setup? > > Regards. Yes, except sparseness is only relevant to file-backed vbds in normal use. (There could ostensibly be a similar lazy block allocation option for a target on something like a SAN/NAS and you would expect some performance degradation for some writes.) -- Christopher G. Stach II ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] Bad Disk Performance of domU
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 > - "Francisco Pérez" 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 > ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] Bad Disk Performance of domU
- "Francisco Pérez" 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
Re: [CentOS-virt] Bad Disk Performance of domU
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 mccar...@gmail.com mccar...@clarkson.edu On Wed, May 20, 2009 at 12:35 PM, Francisco Pérez wrote: > LVM on dom0 or domu? > > 2009/5/20 Christopher G. Stach II > > - "Francisco Pérez" 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 > > ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] Bad Disk Performance of domU
LVM on dom0 or domu? 2009/5/20 Christopher G. Stach II > - "Francisco Pérez" 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
Re: [CentOS-virt] Bad Disk Performance of domU
- "Francisco Pérez" 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
Re: [CentOS-virt] Bad Disk Performance of domU
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. Regards Francisco. 2009/5/19 Christopher G. Stach II > - "Francisco Pérez" wrote: > > > OK, here it is: > > > > name = "vm01" > > uuid = "2fa05fe5-9b52-3527-5bf5-efb88555c567" > > maxmem = 5836 > > memory = 5836 > > vcpus = 1 > > bootloader = "/usr/bin/pygrub" > > on_poweroff = "destroy" > > on_reboot = "restart" > > on_crash = "restart" > > vfb = [ ] > > disk = [ "tap:aio:/var/lib/xen/images/vm01.img,xvda,w" ] > > vif = [ "mac=00:16:3e:15:6f:cd,bridge=xenbr0" ] > > > > Thanks. > > What kind of "disk performance"? Read? Write? Random? Linear? > > As for general tuning, use block devices (LVM) unless you have to do > otherwise. Do you do a large amount of I/O in general? Do you have dom0's > CPU pinned to an unshared core? > > -- > 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
Re: [CentOS-virt] Bad Disk Performance of domU
- "Francisco Pérez" wrote: > OK, here it is: > > name = "vm01" > uuid = "2fa05fe5-9b52-3527-5bf5-efb88555c567" > maxmem = 5836 > memory = 5836 > vcpus = 1 > bootloader = "/usr/bin/pygrub" > on_poweroff = "destroy" > on_reboot = "restart" > on_crash = "restart" > vfb = [ ] > disk = [ "tap:aio:/var/lib/xen/images/vm01.img,xvda,w" ] > vif = [ "mac=00:16:3e:15:6f:cd,bridge=xenbr0" ] > > Thanks. What kind of "disk performance"? Read? Write? Random? Linear? As for general tuning, use block devices (LVM) unless you have to do otherwise. Do you do a large amount of I/O in general? Do you have dom0's CPU pinned to an unshared core? -- Christopher G. Stach II ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] Bad Disk Performance of domU
OK, here it is: name = "vm01" uuid = "2fa05fe5-9b52-3527-5bf5-efb88555c567" maxmem = 5836 memory = 5836 vcpus = 1 bootloader = "/usr/bin/pygrub" on_poweroff = "destroy" on_reboot = "restart" on_crash = "restart" vfb = [ ] disk = [ "tap:aio:/var/lib/xen/images/vm01.img,xvda,w" ] vif = [ "mac=00:16:3e:15:6f:cd,bridge=xenbr0" ] Thanks. 2009/5/19 Luke S Crawford > Francisco Pérez writes: > > > No, the domu's are para-virtualized guest. > > Are you using file:// devices? > > I ask because I use lvm-backed phy:// devices and I get near native > disk performance. Attach the config file for the domain > (usually /etc/xen/domainname) > > ___ > 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
Re: [CentOS-virt] Bad Disk Performance of domU
Francisco Pérez writes: > No, the domu's are para-virtualized guest. Are you using file:// devices? I ask because I use lvm-backed phy:// devices and I get near native disk performance. Attach the config file for the domain (usually /etc/xen/domainname) ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] Bad Disk Performance of domU
No, the domu's are para-virtualized guest. 2009/5/19 Luke S Crawford > Francisco Pérez writes: > > > Hi list. > > > > Im Running xen on a brand new dell PE 1950 with 146 GB SAS Disk on raid1. > > The performance on the I/O on the domU is really poor, but in dom0 the > > performance is great. > > > Are you using HVM? > ___ > 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
Re: [CentOS-virt] Bad Disk Performance of domU
Francisco Pérez writes: > Hi list. > > Im Running xen on a brand new dell PE 1950 with 146 GB SAS Disk on raid1. > The performance on the I/O on the domU is really poor, but in dom0 the > performance is great. Are you using HVM? ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
[CentOS-virt] Bad Disk Performance of domU
Hi list. Im Running xen on a brand new dell PE 1950 with 146 GB SAS Disk on raid1. The performance on the I/O on the domU is really poor, but in dom0 the performance is great. Any ideas? Regards Francisco. ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
