Dear list,
did anybody of you see a similar behaviour? I have a test server with a
single XEN VM running. In it, there's a PostgreSQL DB running a CLUSTER
command, which basically copies the table in a new order. The domU VM
said it's 35MB/s read and 35MB/s write, but the dom0 said it's about
TWICE the amount on *read* only (79MB/s read, 35MB/s write). The command
with which I watched was
iostat -kx 5 555
on both domU and dom0. The values were most of the time nearly exaclty
domU-reads * 2 = dom0-reads. Writes were the same numbers both in domU
and dom0. Of course the values vary a bit because the iostat command
doesn't run exactly at the same time in domU and dom0, but I watched a
long time and it's about twice as much reads on dom0. I would understand
the other way round, that could be because of caching in dom0, but this
results are strange. Anybody got an explanation?
Real Server dom0:
Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz
avgqu-sz await svctm %util
sda 0,00 0,00 0,00 0,00 0,00 0,00 0,00
0,00 0,00 0,00 0,00
sdb 0,00 1,80 10254,40 231,80 79640,00 40258,40 22,87
1,16 0,11 0,04 46,96
XEN VM domU:
Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz
avgqu-sz await svctm %util
xvda 0,00 0,00 0,00 0,00 0,00 0,00 0,00
0,00 0,00 0,00 0,00
xvdb 0,00 0,00 839,92 0,00 35794,01 0,00 85,23
4,90 5,83 1,18 99,00
xvdc 0,00 0,00 0,00 0,00 0,00 0,00 0,00
0,00 0,00 0,00 0,00
xvdd 0,00 0,00 0,00 821,36 0,00 35823,55 87,23
51,17 61,97 1,21 99,48
Later I tested again:
Real Server dom0:
Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz
avgqu-sz await svctm %util
sda 0,00 0,20 0,00 0,40 0,00 2,40 12,00
0,00 0,00 0,00 0,00
sdb 0,20 0,00 3246,31 68,66 24988,42 7826,75 19,80
0,38 0,11 0,07 24,43
XEN VM domU:
Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz
avgqu-sz await svctm %util
xvda 0,00 0,00 0,00 0,00 0,00 0,00 0,00
0,00 0,00 0,00 0,00
xvdb 0,00 0,00 0,00 0,00 0,00 0,00 0,00
0,00 0,00 0,00 0,00
xvdc 0,00 0,00 0,00 0,00 0,00 0,00 0,00
0,00 0,00 0,00 0,00
xvdd 0,00 0,40 277,84 365,27 11681,44 15674,65 85,07
26,68 41,49 0,83 53,49
--
// Michael Monnerie, Ing.BSc ----- http://it-management.at
// Tel: 0660 / 415 65 31 .network.your.ideas.
// PGP Key: "curl -s http://zmi.at/zmi.asc | gpg --import"
// Fingerprint: AC19 F9D5 36ED CD8A EF38 500E CE14 91F7 1C12 09B4
// Keyserver: wwwkeys.eu.pgp.net Key-ID: 1C1209B4
_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users
|
Home