Philip,

a wafl scan reallocate is just a defragmentation. Did NetApp ask you to run a wafl scan measure_layout? What was the result? BTW, I do not remember any improvement with reallocate in ONTAP 6.x It moves blocks around and comes back with pretty much the same fragmentation as it was before. It really works in 7.x

However, to rule out fragmentation you need the measure_layout value.

Herbert

-----Original Message----- From: Philip Boyle [mailto:philip.boyle@eircom.net] Sent: Tuesday, February 21, 2006 9:06 AM To: toasters@mathworks.com Subject: wafl scan reallocate

Hi guys,

I am seeing increased cpu on a filer. It appears to jump when the filer kicks off a number of snapmirrors. I've updated the threshold so that the mirroring runs a little more frequent and this appears to have reduced the high cpu issue. Note, I'm only running approximately 4 snap mirror threads on a clustered environment so I'm not hitting any mirroring thread limitations.

This increase in cpu is unexpected as the filer is running around 50% less snapmirror threads and 40% less volumes from 6 months ago. so if anything I should see a drop in cpu activity.

Support are advising me to run a 'wafl scan reallocate' as one volume is close to 80% full. I'm not convinced and reluctant to kick off wafl commands.

For your information, I'm running 6.5.3P4 on a 940C cluster.

Has anyone else had similar issues or have ran 'wafl scan reallocate'. Any recommendations for debugging?

I've passed on the relevant 'sysstat' data for a 24hr period to Netapp Support.

Regards, Philip