HPE EVA Storage

MSA 2000 - Snapshot/Cloning puzzle

Frequent Advisor

MSA 2000 - Snapshot/Cloning puzzle

Hi all, I have a 2012FC storage with double controller.

- I have 6 SAS disks in it.

- I made 2 Virtual Disks out of them (3 disks in RAID5 each VD). One Virtual Disk belongs to Controller A, and the other one to B, for performance reasons.

- Then I have another VD made from 3 SATA disks that I wish to use for snapshots/clones of various Logical Volumes residing on the SAS disks that I mentioned before. Let's say it belongs to Controller A.

- The remaining slots are Hot Spares

Now, to take snapshot/clones of the Logical Volumes on the SAS disks, I created a "Snap Pool" on the SATA Disks

But the problem is that apparently, I can't take snapshots of the LV's belonging to the VD's on Controller B. System complains that I MUST choose a snap pool on the SAME CONTROLLER, as destination.

I can't add more SATA disks at the moment (I should buy an additional Drive Enclosure for them, and this I can't do)

1) Any ideas or suggestions? I'd like to still be able to spread my production SAS LV's on both the controllers (performance)

2) If no workaround is possible, can anyone give me an idea of the performance loss if I put everything on the same controller?

3) One final question. To take snaps/clones, it is necessary to make a "standard" Volume become a "master" Volume. Does this imply performance loss? Is it a recommended practice to turn ALL the Volumes to be "master", or is it preferable to be careful with "master volume" proliferation?

Thank you very much for your help.

Re: MSA 2000 - Snapshot/Cloning puzzle

Hi Rob, Without rejigging your disks to have sas and sata on the same controller to allow for a pool to be available I don't believe you would be able to do it without buying acouple of extra SATA disks (A HP expert might be able to correct me on this though.), but I believe that is the case. Regarding performace issues it really comes down to your throughput and I/Os. each controller can handle 15k I/Os a sec (I am basing this on the MSA2012sa model I use). So aslong as you dont exceed this amount by moving all disks to one controller then you will probably not have a problem with performance, or exceed the 4Gb/sec FC throughput. I am not sure about question 3 so I wont attempt to answer it, but no doubt there is someone that has experience with the master / standard volume best practises.
Frequent Advisor

Re: MSA 2000 - Snapshot/Cloning puzzle

Chris, thanks for your useful reply. After reading your insight regarding performance of a single controller I think that for now it'll be OK for me to put the 3 VD's on the same controller.

If in the future I'll be hitting the I/O of FC bandwidth limit, then I'll buy the needed additional SATA and change ownership for one of the 2 SAS production VD's.

I still hope somebody will answer to my question (3), and maybe also elaborate a bit on how to make a "master" volume turn back to be a "standard" one (can't find this option anywhere!).

Looking forward to an answer from some of the gurus here...

Thanks again!