[Linux-cluster] DLM tuning

[Bryn M. Reeves]

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On 01/25/2012 09:00 PM, Digimer wrote:
> Hi all,
> 
> EL6 DLM question. Beginning adventures in DLM tuning... :)
> 
> I am trying to optimize DLM for use on nodes which can hit the
> disks hard and fast. Specifically, clustered LVM with many LVs
> hosting many VMs where the VMs are simultaneously disk i/o
> intensive. I am testing though with bonnie++ to induce a high load
> on a GFS2 partition though.

Wouldn't it be more useful to test the clustered LVM scenario (e.g.
using a block device benchmark tool to simulate VM I/O load)?

GFS2 and clvmd use the locking service in quite different ways - in
particular I/O on a GFS2 file system involves locking operations but
this is not true for clvm volumes unless they use a cluster aware
device-mapper target like cmirror.

I'd only expect DLM performance to become a consideration here if
there were many clustered LVM operations taking place on different
nodes at the same time.

Regards,
Bryn.
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