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Re: [Linux-cluster] GFS2 locking in a VM based cluster (KVM)



On Tue, 04 Jan 2011 10:24:03 +0000, Steven Whitehouse <swhiteho redhat com> wrote:
Hi,

On Tue, 2011-01-04 at 05:00 -0500, Thomas Sjolshagen wrote:
Hi,

Posted this on IRC just now, but was recommended to try another approach.

I'm wondering if the locks/sec rate I'm seeing between two virtual
machines is what I should expect - details below:

I've got a 2-node cluster that is actually two KVM VMs (Fedora 14 in
the guests/vms). Between the two VM's, I'm sharing - iSCSI based
external array using virtio_net drivers in the guests/vms - two GFS2
file systems. After setting <dlm> and <gfs_controld> as listed below
in cluster.conf (and, of course, rebooting the whole cluster), I'm
still only seeing 600-650 locks/sec when using the ping_pong utility.

<dlm plock_ownership="1" plock_rate_limit="0" protocol="sctp"/>
<gfs_controld plock_rate_limit="0"/>

The same settings & configuration on the physical hosts (a separate
cluster, but using the same iSCSI array) is seeing 5.5-6K locks/sec.

I'm also curious as to why, when starting ping_pong on the virtualized node1, I see ~20-40K locks/sec, but if I start and then stop ping_pong on the virtualized node2, node1 never returns to anything close to the
20-40K locks/sec. Is that (also) expected?

Did you have the second node mounted when you got the faster locking
rates on the first node?

Yes, both nodes mounted (before and after starting ping_pong on the 2nd node, no umount inbetween)

// Thomas


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