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xen-users
Re: [Xen-users] Poor disk io performance in domUs
Tom,
Are the disk I/O numbers quoted below aggregate for all machines, or
just for the mailserver.
so far we measured separately in dom0 and in the mail-domU.
The 20 MB/s happen as soon as there is concurrent io from two or more domUs.
Andrej
-- -- Tom Mornini, CTO -- Engine Yard, Ruby on Rails Hosting -- Support,
Scalability, Reliability -- (866) 518-YARD (9273) On Jun 20, 2007, at 10:49 PM,
Andrej Radonic wrote:
> Hi,
>
> in a previously well behaving xen setup we are suddenly
> experiencing massive loss of disk performance.
>
> Setup: two identical machines (dell, 2 quadcore cpus each, 8 GB RAM
> each), attached to *one* SAS storagebox (Raid5 SAS disks), CentOS
> 5, Xen 3.04 running three domUs each.
> Storage partitions are exposed as block-devices to the guests.
> Filesystem is ext3.
>
> Since a domU running a rather heavily loaded mailserver (many small
> files, many reads/writes) has been added, io performance has
> deteriorated significantly.
>
> In dom0 about 100 MB/s can be achieved, in domU only about 50 MB/s.
> This looks even worse when there are massive concurrent / parallel
> io jobs, then throughput goes down to 20 MB/s.
>
> During all this the cpus are mostly idle...
>
> Any ideas? I know some performance degradation is to be expected
> but shurely not on this scale?
> Thanks,
> Andrej
>
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-users
interSales AG Internet Commerce
Andrej Radonic
Vorstand
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