I need to replace some disks and need insight into nuances and issues that might arise from doing that with partitioned disks.
Background: we have a 4-node AFF cluster where support is ending on two nodes on 1/31. We are going to migrate all volumes to the remaining 2 nodes and move the shelves over after depopulating them. There is currently one shelf per node, all the same size, except for a single tiny additional shelf attached to the nodes we are depopulating. I'm going to use this as my "lifeboat" to move the root aggregate to from the first shelf I depopulate so the node continues to function after removing the shelf. We are running OnTAP 9.5P14.
Each aggregate occupies half of each shelf. After depopulating one aggregate and moving the root aggregate on one node to the tiny shelf, my last step before removing the shelf is swapping the 12 disks belonging to the other aggregate for 12 spare disks. The end result: the remaining aggregate will be on one shelf and the shelf I'm removing will only consist of spare disks.
To do this, I plan to turn off disk autoassign, perform a storage disk replace on all twelve disks, then remove the disk owners on the spares so I can move the shelf. What makes it interesting is the fact that these are partitioned disks. Both aggregates use ADP. When I move the root aggregate from one node, I assume the partitions remain and are just empty.
The question is: does it make sense to also perform a storage disk unpartition on all 23 disks that used to belong to the decommissioned data aggregate BEFORE doing the storage disk replace? Is it necessary? Would it make more sense to wait until the disk replace is over and then do the unpartition? I want the disks unpartitioned before moving the shelves to the remaining two nodes, but I just want to get a sense of when it makes the most sense to run the command. Would love to hear any insights!
The best practice is to zero the disks before removing them from the original storage system. Otherwise there will be foreign aggregates that will have to be removed. Here is a kb about removing foreign aggregates.
Yes, it is best practice to un-partition the drives before decommissioning them so you don't run into any issues when they are re-purposed. Yes, please wait until the "disk replace" is finished, in addition to verifying everything is healthy on the new disks before you un-partition the disks planned for removal in the event any recovery efforts are needed.