[gpfsug-discuss] Any guidelines for choosing vdisk size?

Jan-Frode Myklebust janfrode at tanso.net
Mon Jul 1 08:56:22 BST 2019

I would mainly consider future upgrades. F.ex. do one vdisk per disk shelf
per rg. F.ex. for a GL6S you would have 12 vdisks, and if you add a GL4S
you would add 8 more vdisks, then each spindle of both systems should get
approximately the same number of IOs.

Another thing to consider is re-allocating capacity. If your vdisks are
very large, it might be difficult to free up a full vdisk if you need to
reorganize and create new filesystems, or add more 3way replicated

But mainly I create large vdisks.. haven’t been able to show any
performance difference between one vdisk per RG vs. 10 vdisks per RG.


man. 1. jul. 2019 kl. 07:42 skrev Ryan Novosielski <novosirj at rutgers.edu>:

> Good morning,
> Was wondering if anyone could point me to any tips or provide some
> regarding choosing vdisk size? My understanding is that too small is a
> waste of resources in the form of overhead, and that there is an upper
> limit. but that generally within a pool, you want them to be the same size,
> so that if you aren’t allocating the entire storage space on the system
> straight off, you’ll need to choose a reasonable size or be left with
> unusable space (eg. you will waste space if you went with, say, 200 GB
> vdisk sizes on a 500 GB array).
> Anyone have any tips? Do people just generally allocate the whole thing
> and have one 2 vdisks (redundancy)? Seems you have some more flexibility if
> you don’t do that and have to, say, create a storage pool or filesystem
> from scratch to take advantage of features in a newer FS version or what
> have you.
> Thanks for the help — spent a lot of time looking for this previously, but
> never asked on the list.
> --
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