[gpfsug-discuss] Mmvdisk and mmchdisk

Simon Thompson S.J.Thompson at bham.ac.uk
Fri Aug 7 14:07:08 BST 2020

I have a question about mmvdisk and mmchdisk.

We have some data on a bunch of vdisks which were migrated from legacy to mmvdisk commands.

We need to move the data off those vdisks to another storage system.

Our plan was:
Create a new pool on with the vdisks on the new storage system
Change the default placement policy to point to the new pool
Use MIGRATE policy to move file-sets over to the new vdisks in the new pool

How do we then go about stopping the old vdisks and checking the data is all off them? Is using mmchdisk safe to use with vdisks, or is there some equivalent mmvdisk command we should be using?

I’m thinking maybe what we do is add a temporary vdisk on the new system in the same pool as the older one thought with a different failure group, and then empty the disks in classical style before deleting them.

Why … (before someone asks), the older system is a hybrid SSD+HDD model and we want to add shelves to it. And online expansion isn’t supported/requires recabling as well. So we move all the data to the new system, and then we want to *selectively* move data back to the older one - not all though … hence the new pools.

I’m assuming also we can remove/delete vdisks from a vdiskset from specific recovery groups. The migration from legacy mode looks to have bunched disks across different RGs into the same vdiskset even though they have different failure groups applied to them.


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