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

[Tim Post <tim.post@xxxxxxxxxxxxxxx>]

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


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