How do you remove an improperly sized LUN from an aggr?

[bob_mckim]

I have a customer who accidentally added a LUN to an existing aggr that was incorrectly sized.  What is the correct procedure to replace that LUN with a correctly sized one?  They can't resize the LUN on the existing array as it's out of space.  Do I create a correct sized LUN on another array, add it as a spare and then do a disk fail against the wrong sized LUN?  I've never tried this on a gateway.

[isaacs]

Hi Bob,

Unfortunately, because were only using RAID0 we do not have the ability to swap individual array LUNs in and out of a RAID Groups as we can with regular spindles.  As long as this LUN was reasonably close in size, it shouldn't be a problem.  Differently sized LUNs are only a problem as the aggregate fills up.  If one LUN is much smaller, it may fill up first.  If there are no free blocks to write to, the IOPS that LUN would provide on write operations are lost.  So it can potentially affect performance. 

Hope that helps!

Dan Isaacs

isaacs@netapp.com

[bob_mckim]

Unfortunately they added a 13.3GB LUN to an aggr composed of thirteen 710GB LUNs. 

df -g -A

Aggregate                total       used           avail      capacity 

aggr6                   7713GB     7173GB      540GB      93%

[isaacs]

Ok, it won't hurt much.  That LUN will fill up soon enough, and it just won't be able to provide write IOPS if it isn't being written to.  As long they understand the only problem is that the disk IOPS supporting that LUN won't be available in some situations.  It's not a big problem in most cases.