MSA 2040 with D2700 SAS Expansion Storage Provision

[IT_Vision]

Hello,

We recently installed a D2700 Expansion shelf (25 drives @ 600GB) which is attached to our MSA 2040.

When provisioning the storage for the D2700 is it best to spit the disks up per Pool A and B?  I find that when pool A is running low on space I am unable to borrow space from pool B, I am assuming this is by design.

The MSA (2040) Head Unit was configured using HP best practice guide for VMware environments, Disk Group 1A and Disk Group 1B.

Now with the expansion attached am I basically going to be creating new Disk groups,...Disk Group 2A and Disk Group 2B and associate with their respective Pools? A/B?

Any help in provisioning the expansion would be greatly appreciated.

[Shawn_K · Accepted solution]

Hello,

By design Pool B cannot 'borrow' space from Pool A or visa versa. 

How you wish to carve up the space on the D2700 will really depend on your needs. You should think about how each Pool will need to grow. For example, a database on Pool A may be for storing inventory, while the database on Pool B may be for transactions. As your business grows, you may need to increase your inventory by 10% which will lead to a transaction increase (hopefully) of 25%. This means both pools will need additional disk groups but you will need more allocated space on Pool B. Using this example I would then create a new disk-group for Pool A (10 drives) that is smaller than the disk-group created for Pool B (14 drives) + 1 global spare. For RAID6 stay within the Power of 2 - number of data drives (nonparity) contained in a disk group should be a power of 2.

To provide some best practices I do suggest you leave some disks available and assign them as global spares. To provide better redundancy I would create all disk-groups as RAID6. Be sure you have both background scrub and disk scrub enabled as well as alerts set to a WARNING level.

Good luck!

Cheers,
Shawn

I work for Hewlett Packard Enterprise. The comments in this post are my own and do not represent an official reply from HPE. No warranty or guarantees of any kind are expressed in my reply.

[IT_Vision]

Hello Shawn_K,

Greatly appreciate the respond and clear example.

I have two global spares assigned in the head unit.  Would it be necessary to assign a drive in the expansion unit as a global spare as well?

Thank you

[SUBHAJIT KHANBARMAN_1]

It's always good to assign Global Spare as per the Disk Group present in the system. For example: if you have two diskgroup and all created with same type and size then better to have 2 Global Spare configured. Also you need to plan spare drives according to the RAID configured in Disk Group as well.

It doesn't matter where the Global Spare located. It can be in the Controller Enclosure or Head Unit. Also they can be at extra Drive Enclosure as well. Also Global Spare can be configured Controller Enclosure as well as drive enclosure.

Hope this helps!
Regards
Subhajit

I am an HPE employee

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[IT_Vision]

Hello Subhajit,

Thank you for the reply and insight on spare disk allocation.

Very helpful information.

Regards