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Re: [Xen-users] need advise with a redhat domU


  • To: xen-users@xxxxxxxxxxxxx
  • From: "Mike Egglestone" <mike@xxxxxxxxx>
  • Date: Fri, 08 Feb 2013 12:38:52 -0800
  • Delivery-date: Fri, 08 Feb 2013 20:40:11 +0000
  • List-id: Xen user discussion <xen-users.lists.xen.org>

"Nick Couchman" <Nick.Couchman@xxxxxxxxx> writes:
I think you need to better categorize the statement "performance is crappy."  Dig into the performance some and figure out where your bottleneck is - disk, network, CPU, memory??  The standard tools you'd use on a physical machine should work fine on a VM - iostat, vmstat, top, free, sar, etc., etc.  Once you nail down where the problem is, you can post back and folks will probably have some better suggestions on how to alleviate specific bottlenecks.  Also, let us know what you're doing with the VM.  Running a basic web server?  Oracle database server?  Compiling code?  The tuning will be very different based on where the bottleneck is and what you're trying to do with the system.

Sorry, should have been more specific in my OP.

Redhat DomU:
The network speed at best is around 17MB/sec.
And the disk IO is around 140MB/sec (running dd command to create a zero'd file)

The DomO network is speed is normal gigabit at around 80MB/sec
and the disk IO is around 400+MB/sec. (8 disk RAID 10)

My other DomU's such as an hvm Windows 2008 R2 server, and
my hvm Debian 6.0 DomU all have normal benchmarks for a typical domU.
Both Windows and Debian DomU using PV drivers.
Disk Speeds around 230MB/sec and network IO around 70MB/sec

Its just this one redhat domU thats not performing well. I'm blaming
the old kernel on it. (2.6.18) so perhaps no PV drivers in that kernel.

This redhat server will mostly be a frontend webserver fetching data from a database on another
different physical server. So, maybe this VM is fine the way it is.
I mostly concerned about disk IO and network speed.
The network speed and disk IO is considerably slower than my Debian domU.
I guess its not that bad after all, but just curious if I can get the full speed out
of the redhat kernel. By either installing PVHVM drivers into the redhat kernel, or making
the DomU a PV guest.  

I've been trying to follow the guidelines here:

Thanks,
Mike

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