Re: [Xen-users] Poor performance with Fibre-channel in domU and dom0

[Simons IT-Service <info@xxxxxxxxxxxxxxxxxxxx>]

Am Donnerstag, den 15.02.2007, 12:26 +0800 schrieb Tim Post:
> On Wed, 2007-02-14 at 17:20 +0100, Simons IT-Service wrote:
> > Hello,
> > 
> > I have a server with 4GB of Memory, two Intel QuadCore Xeon CPUs and a LSI 
> > FibreChannel 4GBit HBA Card connected to a SAN-Box.
> > 
> > When I install this with a normal Linux (CentOS 4.4) with kernel 
> > 2.6.9-42.0.3.ELsmp and the mptfc driver, which is deliverd with this 
> > kernel, everything works fine.
> > 
> > I can copy a 600 MB file from one directory to an other on the same 
> > partition in 6 seconds.
> > 
> > When I install on the same server a Xen-kernel (2.6.16.29-xen) with the 
> > mptfc driver, which is deliverd with this kernel, the I/O performance to 
> > the SAN is very,very,very slow.
> > 
> > When I copy in a domU a 600 MB file from one directory to an other on the 
> > same partition it take 90 seconds.
> > 
> > The config file for the disk in my domU is this:
> > 
> > disk = [ 'phy:/dev/OracleVG/OraAdmin10gR2,/dev/sda1,w', 
> > 'phy:/dev/OracleVG/OraDumps10gR2,/dev/sda2,w', 
> > 'phy:/dev/OracleVG/OraProduct10gR2,/dev/sda3,w', 
> > 'phy:/dev/OracleVG/OraSoftware10gR2,/dev/sda4,w', 
> > 'phy:/dev/OraDataVG/pdevkh1,/dev/sdb1,w', 
> > 'phy:/dev/OraDataVG/pskh,/dev/sdb2,w', 
> > 'phy:/dev/OraDataVG/temp,/dev/sdb3,w', 'phy:/dev/sda13,/dev/sdc1,w' ]
> > 
> 
> I'm not 100% sure its going to *significantly* improve things, but
> giving the dom-u some swap space may help, unless this one :
> 
> 'phy:/dev/sda13,/dev/sdc1,w'
> 
> is handling swap locally, but it looks like it may be the boot vbd,
> unless sda1 also contains the root filesystem for the guest?
> 
> Best,
> --Tim
> 

Hello Tim,

thanks for your answer.

Every DomU in my solution have a 2 GB Swap
('phy:/dev/sda13,/dev/sdc1,w') for him self.

And every Dom0 and DomU boot over NFS, I use openQRM 3.1.2 from
www.openqrm.org

Any idea?

Best
Dietmar Simons
(Neuss, Germany)


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