Re: [Xen-users] Slow IO Performance

[Anand <xen.mails@xxxxxxxxx>]

Here are results from my devel box with an old seagate 20gb hdd. Both results are on the same machine, first one is from inside domU, and second is from dom0. These results are without any scheduling imposed on any domain and with only one domain active on dom0. The domU is a bare bone centos with min services running.

A lot of difference in results.

[from inside domU]
hdparm -tT /dev/sda1

/dev/sda1:
 Timing cached reads:   896 MB in  2.01 seconds = 445.77 MB/sec
 Timing buffered disk reads:   54 MB in  3.03
 seconds =  17.82 MB/sec

[from inside dom0]
hdparm -tT /dev/hdb

/dev/hdb:
 Timing cached reads:   932 MB in  2.00 seconds = 466.00 MB/sec
 Timing buffered disk reads:   68 MB in  3.07 seconds =  22.15
 MB/sec

On Fri, 13 Jan 2006 22:28:14, Adam Wendt <adam@xxxxxxxxxxx> wrote:

On Fri, 13 Jan 2006 21:14 , Tomas Florian <tflorian@xxxxxxxxx> sent:

>Hello,
>
>I'm having trouble with slow IO performance under Xen 2.0.7 with 2.6
>kernel.  I'm running 3 physical machine.  I did hdparm -tT in my Dom0 on
>both servers and this is what I get:

<snip>

I would check to make sure your kernels have the right ide drivers builtin or as
modules, i've seen this type of performance on a few machines and the fix was to
double check the kernel config.

Adam Wendt
IPCoast, Inc.




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-- 

regards,

Anand
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