In our case, it's an exploding M$ Exchange Information store... It started out on 2 36G disks, now it's up to 4. Mailbox quotas must be nice...
I was turned on to the wafl commands by one of our local PSE's last week, we were having horrible performance reported while our Exchange snapshot verifications were running. A statit showed 1 disk at 100% activity, and the next one at 66%.
I ran a 'wafl scan measure_layout', and got:
wafl_filesystem_sca:info]: WAFL layout ratio for volume vol7 is 4.87. (A ratio of 1 is optimal).
So, I run a 'wafl scan reallocate vol7', let it chug for an hour, then run another 'wafl scan measure_layout', and it's still 4.87 :( I've done this twice now, with no change in waffling. We're running 6.1.2.
At the advice of my PSE, I'm opening a ticket with NOW.
John Witham Sr. Data Networking Engineer Takeda Pharmaceuticals North America, Inc. e://jwitham@takedapharm.com V://847.383.3304 F://847.383.3205
A computer lets you make more mistakes faster than any invention in human history, with the possible exceptions of handguns and tequila.
-Mitch Ratcliffe
-----Original Message----- From: barry@lustig.com [mailto:barry@lustig.com] Sent: Wednesday, January 23, 2002 12:15 PM To: Matt Musgrove Cc: Jeff Kennedy; NDMP List Subject: Re: Repost: wafl scan question
This sounds like it would be useful for volumes that started out with low performance needs with a small number of disks in the array that ended up with large raid sizes. I imagine that files would get striped across the larger number of drives after the reallocate.
barry
On Wednesday, January 23, 2002, at 02:00 AM, Matt Musgrove wrote:
From my ONTAP course notes:
wafl scan reallocate takes a volume or file and reallocates it on the disk to increase its layout efficiency (ie. defrags). However, you should only run this command on the advice of NetApp. It should only be run if volume capacity is <80% and during a non-peak period (filer impact similar to a vol copy command).
hope that helps
Matt Musgrove
Jeff Kennedy wrote:
Don't know if this didn't get through or what so I'm reposting.
Thanks.
Jeff Kennedy wrote:
What exactly does 'wafl scan reallocate' do? Does it actually re-write data in a more efficient manner/layout? Or does it redo inodes and pointers in a more efficient layout without moving data?
I know that a reallocate is unnecessary if the measure_layout is low (most of mine are under 2) but on occassion I get higher numbers and wonder what it does to fix this.
Thanks.
--
Jeff Kennedy Unix Administrator AMCC jlkennedy@amcc.com
This message is for the designated recipient only and may contain privileged or confidential information. If you have received it in error, please notify the sender immediately and delete the original. Any other use of the email by you is prohibited.