|Subject:||Re: Help with XFS in VMs on VMFS|
|From:||Jan Perci <jperci@xxxxxxxxx>|
|Date:||Thu, 28 Mar 2013 23:30:01 -0400|
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Thank you for your responses. Since this list is for XFS, I do not wish to go off topic too far into VM's. But I will provide more context.|
A key factor is the need for >2TB file systems that can be snapshot and reverted quickly. We have other FC arrays attached to compute nodes without this requirement, and they have XFS directly on the FC logical volumes made accessible to native nodes and VM nodes via RDM.
Our FC arrays do not have native snapshot features, so we must use a software layer whether that is Linux LVM, ESXi, or something else. And because of our unique usage patterns and constraints, we have settled on VMware over other virtualization technologies. We are using ESXi (free version) but can upgrade to ESX if necessary. However, the upgrade wouldn't fix the 2TB snapshot limit.
We are certainly not in the true HPC realm, but we do have about 20 physical compute nodes that do both random and sequential I/O. An example query might identify a 10-500GB data set comprised of 100-500KB files. Some work sets are processor bound with disk I/O accounting for less than 5%. However, others are spending about 50% on disk I/O, so improving performance would be helpful - again in the context of the snapshot requirement.
Point well understood about the risks of striping multiple 2TB VMDK files together. But because of the constraints, it's either 2TB VMDK's or 2TB RDM's in virtual compatibility mode, and they both seem about equally risky. Do you have better suggestions?
Back to XFS, in this context, is there any benefit in tuning some parameters to get better performance, or will it all just be overshadowed by poor performance of the VMDKs that tuning isn't worthwhile?
On Thu, Mar 28, 2013 at 8:56 PM, Stan Hoeppner <stan@xxxxxxxxxxxxxxxxx> wrote:
On 3/28/2013 4:45 PM, Ralf Gross wrote:
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