MSA 2050 RAID disk groups

[Jf3]

Hi,

We have purchased 2 SSD 800GB disks and 5 SAS 900GB. What is the best configuration to set the the Disk groups on Pool A?  We were thinking of RAID 1 on the SSD and RAID 5 on the 5 SAS all of these on pool A.

We are thinking of purchasing next year another 2 SSD and 5 SAS 900GB and add these new ones into Pool B. That way we have the recommended balance on both controllers?

Could someone advice on the best way to do this? We could not buy any more disks as we didnt have any more money this year.

Thanks,

[HPSDMike · Accepted solution]

Hello.

Unless you purchased the "Advanced Data Services" license, for the 2050, then the only way you can utilize the SSD's is as a read cache tier. If the system is all SSD then you don't need the license but, as soon as you want to use SSD and spinning disks, on the same system then you need the license. The license is included on the MSA 2052 model (which maybe you purchased?). The 2050 and 2052 are exactly the same unit but the 2052 is bundled version that includes 2 SSD drives, and the license, at potentially a cost savings over buying individually.

Anyway, your plan sounds pretty good. If you have a 2052/ADS License, then add a RAID1 SSD group to Pool A then add a 5 disks RAID 5 900GB set to Pool A. With this configuration, your data will automatically tier (move up/down) based on access patterns. 

If you don't have the license then create your 5 x 900GB RAID5 set in Pool A and add one SSD as a read cache tier in Pool A.  Save the other SSD as a read cache disk for Pool B. 

Next upgrade, make Pool B look like Pool A and continue staggering the upgrades between pools making sure that you are always keeping your upgrade increments in the same set size and same disk type/size. This will limit chances of future performance issues. 

Also, 4+1 is a nice set size because it meets the MSA "power of 2" rule (8+1 would be more capacity efficient but 4+1 can do if that is your budget). Problem is that set size leaves you with no spare disk. Consider purchasing a single 900GB drive to be a "global hot spare." This will limit your chances of data loss in case you have a drive failure go unnoticed or take a while to getting around to replacing it.

[Jf3]

Thank you, perfect.