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[Xen-users] disk performance (memory problem??)

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] disk performance (memory problem??)
From: "Tomas Srnka / LINUX s.r.o." <toms@xxxxxxxxxx>
Date: Tue, 03 Jun 2008 06:58:49 +0200
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Hello,

I have a strange problem. I'm using XEN on OpenSuSE 10.2 machine for over a year. Everything is fine, until ID of a virtual machine reaches 38-40. Then, my disk performance drops rapidly. From 70MB/sec to 5-6MB/sec. If I restart the host server, it will be fine again, but I don't want to do that.

Here is hdparm test:

baxen01:~ # hdparm -Tt /dev/sda

/dev/sda:
Timing cached reads:   880 MB in  1.99 seconds = 442.31 MB/sec
Timing buffered disk reads:   20 MB in  3.33 seconds =   6.01 MB/sec
baxen01:~ # hdparm -Tt /dev/sdb

/dev/sdb:
Timing cached reads:   822 MB in  2.00 seconds = 410.96 MB/sec
Timing buffered disk reads:   18 MB in  3.32 seconds =   5.43 MB/sec
baxen01:~ # hdparm -Tt /dev/sdc

/dev/sdc:
Timing cached reads:    56 MB in  2.06 seconds =  27.22 MB/sec
Timing buffered disk reads:   16 MB in  3.22 seconds =   4.97 MB/sec

xm list took 6 secs to print the machines.

baxen01:~ # xm list
Name                                      ID Mem(MiB) VCPUs State   Time(s)
Domain-0                                   0     1070     8 r----- 150349.7
hauratonsro                               35      196     1 -b----   1086.3
linuxsro01                                 1     1536     4 r----- 1300479.3
megabookssro                               3      512     1 -b----  49968.2
sageteam01                                41      256     1 -b----     94.2
vermont                                   40      256     1 -b----    896.9
wigwam                                     6      196     1 -b----   8231.0

The configuration of the machine is: 2xIntel xeon 5050 (dualcore+hyper threading), 4GB RAM, 6x400GB (3xRAID1 + LVM on top of it).

Do you have any idea, what the problem can be?

Thank you

--
S pozdravom / Best regards
*Tomas Srnka, LINUX s.r.o.*
Project Manager & Project leader of LinuxOS.sk
website: http://www.LinuxOS.sk, http://www.LINUXsro.sk
e-mail: tomas.srnka@xxxxxxxxxxx
mobile: ++421 949 246 313
ICQ: 262-839-018

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