Re-ordering shelves for NetApp FAS

No-one is perfect. I recently added some shelves to the wrong location of a stack, breaking the design rule of a single speed transition between 3G and 6G shelves, and didn’t find out until after the new disks were added to an existing aggregate.¬†Under normal circumstances, you can officially hot remove disk shelves from a system running ONTAP 8.2.1 or later. Assuming they don’t have data on them, which these ones did.

Fortunately ONTAP doesn’t require symmetric SAS topologies, so I did the following to resolve it:

  1. Aim to recable the IOM B stack
  2. Failover and take node 2 out of service
  3. Disconnect SAS cable from node 1 (yes, node 1) to IOM B
  4. Recable IOM B’s SAS stack
  5. Disconnect node 2’s connection to the IOM A stack
  6. Bring up node 2, failback
  7. At this point, node 1 and node 2 have different, non redundant topologies
  8. Failover node 1 to node 2
  9. Recable IOM A stack
  10. Reconnect redundant connections for IOM A and IOM B to bring node 2 back into MPHA
  11. Failback to node 1

Tada, all done, non-disruptive (system is iSCSI only – CIFS without SMB3 Continuous Availablity would result in session disconnects)

alex

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