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Re: [Xen-users] DomU IO issue

Hi,
what are the mount options (/etc/fstab) on the DomU ?
In the xen-tools "partitions.d" example, "sync" is used, which give poor performance.

this is my fstab (DomU)
# /etc/fstab: static file system information.
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
proc            /proc           proc    defaults        0       0
devpts          /dev/pts        devpts  rw,noexec,nosuid,gid=5,mode=620 0  0
/dev/sda1 none swap sw 0 0
/dev/sda2 / ext3 noatime,nodiratime,errors=remount-ro 0 1

Stefan




Olivier

Stefan Below a écrit :
This is the domU config file:

kernel = "/usr/lib/xen/boot/pv-grub-x86_64.gz"


memory      = '2048'
vcpus=2

disk        = [
                 'phy:/dev/vg0/tsIbex-disk,xvda,w',
                 'phy:/dev/vg0/tsIbex-swap,xvdb,w',
             ]

extra = "(hd0)/boot/grub/menu.lst"
name        = 'tsIbex'

vif         = [ 'ip=192.xxx.xxx.xxx,mac=xx:xx:xx:xx:xx' ]

on_poweroff = 'destroy'
on_reboot   = 'restart'
on_crash    = 'restart'


Dom0 Hardware and configuration:
Q6600 with 8GB RAM
sw Raid10,f2 Layout with 4 disks (i know, hardware raid is better.....) (storage for DomU via LVM)
sw Raid1 with 4 disks for Dom0 root partition

Debian Lenny, xen 3.3.1, with Kernel 2.6.26-1-xen-amd64.

Anything else i should provide?

Thanks,
Stefan



Could use some more detail - DomU config and a description of the storage and hardware would be good.

Best Regards
Nathan Eisenberg
Sr. Systems Administrator
Atlas Networks, LLC
support@xxxxxxxxxxxxxxxx
http://support.atlasnetworks.us/portal


-----Original Message-----
From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Stefan Below
Sent: Tuesday, June 16, 2009 12:50 PM
To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] DomU IO issue

Hello,

i have a a big io issue with my PV-Guest (Ubuntu 9.04). When i write or copy large files, the hdd performance is very slow.

This is my iostat output. It looks like that the datat is not reading and written the same time.

File copy in DomU (PV Guest, LVM)

Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await svctm %util md0 0,00 0,00 1718,00 2816,00 6,71 11,00 8,00 0,00 0,00 0,00 0,00

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0,00    0,00    1,00    0,00    0,00   99,00

Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await svctm %util md0 0,00 0,00 2232,67 0,00 8,72 0,00 8,00 0,00 0,00 0,00 0,00

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0,00    0,00    1,98    0,00    0,99   97,03

Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await svctm %util md0 0,00 0,00 1079,00 4959,00 4,21 19,37 8,00 0,00 0,00 0,00 0,00

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0,00    0,00    1,00    0,00    0,00   99,00

Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await svctm %util md0 0,00 0,00 2866,00 0,00 11,20 0,00 8,00 0,00 0,00 0,00 0,00

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0,99    0,00    0,99    1,98    0,00   96,04

Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await svctm %util md0 0,00 0,00 2719,00 0,00 10,62 0,00 8,00 0,00 0,00 0,00 0,00

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0,00    0,00    0,00    0,00    0,00  100,00

Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await svctm %util md0 0,00 0,00 1264,00 0,00 4,94 0,00 8,00 0,00 0,00 0,00 0,00


File copy from Dom0 shows up a normal behavior:


avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0,99    0,00   13,86   78,22    0,00    6,93

Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await svctm %util md0 0,00 0,00 13504,00 13325,00 52,75 52,05 8,00 0,00 0,00 0,00 0,00

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0,00    0,00   10,00   81,00    0,00    9,00

Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await svctm %util md0 0,00 0,00 11155,45 11163,37 43,58 43,61 8,00 0,00 0,00 0,00 0,00

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0,00    0,00   15,84   76,24    0,99    6,93

Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await svctm %util md0 0,00 0,00 12226,00 12302,00 47,76 48,05 8,00 0,00 0,00 0,00 0,00

I am running xen 3.3.1 on Debian Lenny Dom0, Kernel 2.6.26-1-xen-amd64.

Thanks a lot

Stefan



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