Re: [Xen-users] iscsi vs nfs for xen VMs

[Ozgur Akan <ozgurakan@xxxxxxxxx>]

Hi Jia,

Was there any specific purpose you choose GFS2 + clvmd over NFS ?

In my experience, like a year ago, GFS2 performed very poorly compared to EXT3 under high load and we had to rollback to EXT3. I am pretty sure that NFS would outperform GFS2 if VMs have high IO to the disk images. 

Could you give any IOPS. throughput values you achive to the GFS2 file system with the current configuration?

thanks.,
OZ

On Fri, Aug 7, 2009 at 10:26 AM, Dustin Black <vantage@xxxxxxxxxxxx> wrote:

We are using iSCSI with CLVM and GFS2 very successfully with 10 physical Xen servers and 80 to 100 VMs running across them.  We use file-based disk images, all stored on a single GFS2 file system on a single iSCSI LUN accessible by all 10 Xen servers.

On Fri, Aug 7, 2009 at 10:11 AM, Jia Rao <rickenrao@xxxxxxxxx> wrote:

Thank you very much for the prompt replies.

My intention of moving to iscsi is due to pure performance purpose.
The physical hosts and the storage server are connected through a 1G switch. The storage server uses raid-5 disk array.
My current testing using iozone within VMs on both iscsi and nfs produced similar performance results for sequential and random read.

I was told it will make a big difference if there are 10-15 VMs sharing the storage server. In my case, I have 8-10 VMs.

Any experience with a larger number of VMs in both nfs and iscsi?

Jia.

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