RE: [Xen-users] Windows Disk performance

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

> I've been getting disappointing results on IO reads when using windows
> guests.  I'm getting usually around 70MB/s reads using hdtune.  When
> installing James' PV drivers, the speed drops to about 20MB/s.
> 
> The host system is getting around 350MB/s reads.  I'm wondering if
there
> is such a significant slowdown, or if my tests are somehow flawed.
The
> 70MB/s persisted throughout my VM testing, whether I was using Xen,
> XenSource or VMWare Server.
> 
> So my questions are:
> 
> a.  Is there a bottleneck somewhere which basically caps the windows
> disk performance?
> b. Is my testing methodology flawed.  Is there a better windows tool
> that will measure performance?  What about Linux tool?  I'm currently
> using hdparm -t

If you are using the same tool in Windows then I'm comfortable that a
drop from 70MB/s to 20MB/s indicates a major problem somewhere.

Actually, since I haven't implemented any of the event log stuff yet as
per my last email, could you run DebugView from sysinternals and see if
any logging comes up while you run your performance tool? Make sure
kernel logging is on - you can tell if it is if you go into disk
management and a whole lot of debug info gets output.

James

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