VNX Storage Pool For File

Checked the latest release notes...

For older systems, the maximum LUN size that can be presented to the File pool was 2TB.  For VNX the maximum LUN size is 16TB.  For pre-VNX systems, the AVM algorithm creates enough LUNs in each RG to get LUNs that are less than 2TB in size.  So for an RG of 4+1 146GB drives, you'd get 1 or 2 LUNs (depending on code version).  For a 12+2 R6 of 2TB, where the RG itself is over 20TB usable, you might get 10 LUNs.  In newer code they lifted the 2TB limit and attempt to provision just one LUN per RG regardless of size, up to 16TB per LUN.. So for the 20TB RG, you'd still get 2 LUNs.

Assuming you have more than 1 RG, AVM then snags one LUN from each RG up to 4 RGs, (8 for Symmetrix) and stripes them together.  As the pool grows, AVM concatenates these stripes together so you end up with a large Meta of many concatenated stripes.  It pulls the LUNs from the RG's sort of randomly to round robin IO across the RGs as best it can and prevents itself from striping across two LUNs in the same RG (something you should almost never do).

So it looks like someone either manually created these pool volumes (and it appears to be 5 separate pools unless there are more volumes we don't see here) or AVM was only given LUNs in increments of 2 to build the pools from.

If you are using a block VP Pool behind the file pool, the rules are different.. 1 LUN per pool disk, increments of 5 LUNs per pool (so if you have 32 disks in the pool, you'd get 35 equal sized LUNs).  Then the pool concatenates all those LUNs together, no striping since the block pool is already striped.

1. How did EMC come up with the volume names, v119, v123, etc?

     The UXFS file system used by VNX File uses the v___ nomenclature for all volumes.  Those numbers are assigned based on some internal algorithm in the file code and is not related to the back end as far as I'm aware.

2. Does the VNX stripe accross volumes in the pool? If so, then the volumes would really need to be striped accros the back-end?

     VNX File pools can be striped, concatenated (meta), or a combination of stripes, slices, and meta's.  meta is the name VNX File code uses for concatenated volumes.  a meta, by nature, is not striped by itself..  However a meta can include striped volumes.

3. Is there a max/preferred size disk to present to file? 10.7's are used in this case.

     Typically you will want 2-4 LUNs per RG on the backend when used with File, there's a best practice on this that I need to go find.  If you use a VP Pool on the backend, then you want 1 LUN per disk in the pool I believe, in increments of 5 LUNs.  The size of the individual LUNs is not a huge factor, though there is a maximum limit (16TB I believe, I'll check that in a bit too.

4. Why is volume v1402 and v1406 called a meta when there is only one disk to make up the volume?

     a new backend disk that is added to the VNX File, by default, is added to an AVM pool (automatic volume management).  AVM typically uses concatenated metas.  In this case you only have one LUN per meta, but it's a meta so you can easily add more LUNs to grow the pool.

Pool: Clarata_r6

Volume     Disks     Size     Config

===========================

v119          d8,d12     21.5     Striped

v123          d9,d10     21.5     Striped

v127          d7,d11     21.5     Striped

v1402          d14       10.7     meta

v1406          d13        10.7     meta

The above example is 1 pool (clarata_r6) of 5 volumes, v119, v123, v127, v1402, & v1406. In my case, I will need to create 2 pools, one with a few 6+2's and one pool with one or two 12+2's. Hopefully, I can assign the disks to the "file" storage group, then create the striped volumes and pools manually. Sounds like AVM will take the disks when visible and bunch them into one pool. Can I stop AVM from trying to do it for me?

I am out of the office until 06/24/2013.

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- VNX Storage Pool For File" sent on 6/19/2013 1:44:56 AM.

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Please check the "Volumes and File Systems Manually" manual, which can be found on support.emc.com

As long as there is no data on your disks (luns), you can create volumes and pools manually.