How to move aggregates between NetApp controllers

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DISCLAMER: I ACCEPT NO RESPONSIBILITY FOR ANY DAMAGE OR CORRUPTION OF DATA THAT MAY OCCUR AS A RESULT OF CARRYING OUT STEPS DESCRIBED BELOW. YOU DO THIS AT YOUR OWN RISK.

 

We had an issue with high CPU usage on one of the NetApp controllers servicing a couple of NFS datastores to VMware ESX cluster. HA pair of FAS2050 had two shelves, both of them owned by the first controller. The obvious solution for us was to reassign disks from one of the shelves to the other controller to balance the load. But how do you do this non-disruptively? Here is the plan.

In our setup we had two controllers (filer1, filer2), two shelves (shelf1, shelf2) both assigned to filer1. And two aggregates, each on its own shelf (aggr0 on shelf0, aggr1 on shelf1). Say, we want to reassign disks from shelf2 to filer2.

First step is to migrate all of the VMs from the shelf2 to shelf1. Because operation is obviously disruptive to the hosts accessing data from the target shelf. Once all VMs are evacuated, offline all volumes and an aggregate, to prevent any data corruption (you can’t take aggregate offline from online state, so change it to restricted first).

If you prefer to reassign disks in two steps, as described in NetApp Professional Services Tech Note #021: Changing Disk Ownership, don’t forget to disable automatic ownership assignment on both controllers, otherwise disks will be assigned back to the same controller again, right after you unown them:

> options disk.auto_assign off

It’s not necessary if you change ownership in one step as shown below.

Next step is to actually reassign the disks. Since they are already part of an aggregate you will need to force the ownership change:

filer1> disk assign 1b.01.00 -o filer2 -f

filer1> disk assign 1b.01.01 -o filer2 -f

filer1> disk assign 1b.01.nn -o filer2 -f

If you do not force disk reassignment you will get an error:

Assign request failed for disk 1b.01.0. Reason:Disk is part of a failed or offline aggregate or volume. Changing its owner may prevent aggregate or volume from coming back online. Ownership may be changed only by using the appropriate force option.

When all disks are moved across to filer2, new aggregate will show up in the list of aggregates on filer2 and you’ll be able to bring it online. If you can’t see the aggregate, force filer to rescan the drives by running:

filer2> disk show

The old aggregate will still be seen in the list on filer1. You can safely remove it:

filer1> aggr destroy aggr1

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