2012-05-13 06:31 AM
How are you?
Usually, I prefer to use NetApp Storage Workbench(SW) and Storage Design Studio(SDS) to plan my systems. Both are using the best practices described at NetApp Technical Reports.
At Storage Workbench you can plan your controllers, disks and aggregates. It is a very interesting software because you enter the amount of disks and their types, then SW balances the amount of disks in the raid groups. At SDS, you can plan your volumes, qtrees, LUNs, hosts on the SAN, CIFS shares, and more... It'll produces a document about your implementation.
This tools are available at http://synergy.netapp.com.
I hope it can help you.
NetApp - Enjoy it!
2012-05-13 01:28 PM
For maintenance garage to work, you need 2 hot spares, so best to have 2 hot spares if you want that feature (ability to check a failed drive to see if really failed and pre-fail of disks). That leaves 22 drives left. The max (without a hidden option override) is 20 drives for a RAID_DP SATA aggregate. So with only a single shelf and assuming you put all disks on the same controller, you could go with a single aggr of 18D+2P then have 4 spares. Or if you want to change to the hidden option (search communities which has a post on it - I can't post but someone else has it listed ) then you could go with 20D+2P and have 2 spares.
Depending on growth though you might want to have a different sized raid group. There are great best practice papers (Jay White TRs for SEs/Partners) that give optimal raid group sizes to get the max aggr size per platform. Those raid sizes vary and your NetApp SE or Partner SE can do a quick overview and make a recommendation (above is based on if you want to maximize the one shelf only). Or post your controller model and your future plans for growth and we can make some what if scenarios.