Monday, February 10, 2014

CDOT Raid Groups

A cool bit of trivia about expanding RAID Group sizes.  

For the command storage aggregate modify
For the command storage aggregate add-disks(both quotes from 8.2 command manual)

Which means if you need to balance an unusual number of disks today but will add more disks at some future date, if you want to have small RG’s now and expand them in the future you have to be careful.  For example, if you have 45 disks and want a RG size today of 15 but 20 later, you’d do this:

Storage aggr create –aggregate aggr1 -diskcount 15 –disktype SAS –maxraidsize –s 20
Storage aggr add-disks –aggregate aggr1  -diskcount 15 -disktype SAS –raidgroup –g new
Storage aggr add-disks –aggregate aggr1 -diskcount 15 -disktype SAS –raidgroup –g new

But then we found this:
(Clustered Data ONTAP 82 Physical Storage.pdf)

While this excerpt doesn’t explicitly state you can, I tested in the lab and confirmed: you can manually expand RG sizes of all the RG’s in the aggregate by modifying the max RG size then manually adding disks to each RAID Group.

Storage aggregate add-disks –aggregate aggr1 -diskcount 5 -disktype SAS –raidgroup rg0

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