2016-01-26 03:17 AM - last edited on 2016-01-26 06:06 AM by alissa
I have 1 shelf SSD X24. planning on creating 2 flash pools for 1 agg on each node within a pair, RAID-DP
Should I do: 9 data, 2 dp, 1 spare, or 8 data, 2dp, 2 spares for each pool? can data disks be odd number?
Also, among 24 SSDs, 7 is owned by one node, 17 is owned by the other. Should I split the ownership by half and half before creating the pool or does that matter?
Thanks for sharing!
2016-01-26 02:21 PM
You have to split the ownership if you want 12 disks used for each node.
You can have an odd number of disks in a raid group, that's no problem. Whether you have 1 or 2 spares is a personal choice. One spare would give you more usable capacity. If you know you could get a replacement disk quickly - then 1 spare should be fine. If it might take awhile to get a replacement on site, you may want to have more than 1.
2016-01-28 07:49 AM
Also, if you run on DataONTAP 8.3 you can look at storage pool technology.
2016-01-29 03:25 AM
For a disk to be used as a hot spare for another disk, it must conform to the following criteria:
• It must be either an exact match for the disk it is replacing or an appropriate alternative.
• If SyncMirror is in use, the spare must be in the same pool as the disk it is replacing.
• The spare must be owned by the same system as the disk it is replacing.
2016-02-26 05:55 PM
I would split the shelf - odd #'s to one controller and even #'s to the other controller. Since the SSDs are so expensive, we chose to go with #disks+2DP with 1 spare. The rebuild times are extremely fast on the SSD raidgroup. You would essentially have to lose 3 disks within 4 hours if you only have 4 hour support. Never had a SSD fail in my experience.