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

[Steven Whitehouse]

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?

Steve.