February 5, 2011 Leave a comment
When adding disks to a NetApp array it is usually to add prefomance and capacity. Unless you reallocate the WAFL system will actually not preform much better unless you reallocate your volumes and drives over the newly increased disk space on your aggregate. Otherwise WAFL will only use the new disks until they are as saturated as the existing disk in an attempt to level out the disks. If you only added a couple of disks this can lead to hot spots and lower then expected IO. So reallocating effectively tells wafl to move some of the existing data to the new disks and frees up space equally over all disks.
So here are a few helpfull cammands that you will need to complete this simple optimization task. Depending on the size of your existing volumes and the number of disks you have added this can take some time.
You must be in priv advanced to complete this command:
FILER1> priv set advanced FILER1*>
You need to run the following on each volume within the aggregate before your run this on the aggregate, and this will take some time depending on the size of the data and the numebr of new disks.
FILER1*> reallocate start -f -p /vol/volumename
Here is the command to check the Reallocation status, you can do only one volume or aggr at a time so by using the following command you can see if it is time to move on to the next reallocate
FILER1*> reallocate status -v
Reallocation scans are on /vol/volumename: State: Reallocating: Inode 677805, block 40384 of 10490701 (0%) Flags: doing_force,whole_vol,keep_vvbn Threshold: 4 Schedule: n/a Interval: n/a Optimization: n/a
For snapmirror targets you will need to run the following to break the mirror, after the entire process is complete resync the mirror.
FILER1*> snapmirror break volumename FILER1*> reallocate start -f -p /vol/volumename
For the aggregate reallocation you will run the following command only after running reallocate on all volumes within the aggregate.
FILER1*>reallocate start -A arrgname FILER1*> reallocate status -v
Just remember on any volume that is a snapmirror target you will need to resync after this is complete. I usually do so in the filerview, but this can be done in the command line as well.
To get out of priv advanced:
FILER1*> priv set admin FILER1>