RE: [Xen-users] Xen Disk I/O performance vs native performance

["James Harper" <james.harper@xxxxxxxxxxxxxxxx>]

> Subject: Re: [Xen-users] Xen Disk I/O performance vs native
performance
> 
> Im curious, What PC do you have? Im running a Compaq DL380 and get
crap
> Profomace at the moment.

What sort of DL380, and what sort of disks?

I've got a DL385 with 146G 10K 2.5" SAS disks on a HP RAID controller,
and hdparm -tT /dev/cciss/c0d0 gives me around 900MB/sec for cached
reads, and around 235MB/sec for buffered reads.

hdparm -tT on an lv used in DomU, with hdparm being run from Dom0 gives
me about the same for cached reads, but only 60MB/sec for buffered
reads.

hdparm -tT on the same lv under DomU gives me 35-50MB/sec.

So I'm getting a pretty drastic performance hit from lvm (never noticed
that before... guess I should look into it... maybe it's an artefact of
hdparm) and a small hit from xen blockfront/back.

James


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