Automatically use the same preferred node of source volumes for snapshot target volumes.

This is delivered with new volume group Snapshot 2.0 in 2Q22 (8.5.1)

Just thinking about the proposal, currently the way Commvault and other softwares make referenced snapshots are:

1. run mkvdisk to create a target for flashcopy
2. run mkfcmap to create the snapshot relationship
3. run startfcmap to create the snapshot and give the fcmap target data

The existing design for mkvdisk defaults to round robin preferred node in effort to load balance host workload between nodes/iogrps. In the software today, we provide the ability to add -node to mkvdisk to specify preferred node to override this default.

Given Spectrum Virtualize can't know the end-user intention to create a snapshot when simply making a volume, my opinion is the existing design is correct. I think the real enhancement is required on the 3rd party software to query the volume it intends to make a snapshot of (which it must do already to get size information) for the preferred node and add it to its script to create new volumes.

The alternative implementation to satisfy this request would be to make some new CLI like mksnapshot which combines lsvdisk, mkvdisk, and mkfcmap functionality which to me seems like unnecessary to fit the requirement listed.

While this could be done in theory, my opinion is that for the case of your customer, the right implementation is to make the software that is creating the snapshot read in 1 extra variable from lsvdisk (because it is getting data from this already) to make their mkvdisk command smarter and complaint with out best practices.