Thin Provisioning on an MSA2052

[Paolo_c]

Hi,

I'm looking for some specific advice regarding the QTY and size of disks that would be required to accommodate the virtual volumes listed below on a single MSA2052 (per server) ,  under a Thin Provisioning (raid 5 or raid 6) configuration. (The disks marked as mirrorsets below could also be configured under the same ThP raid 5 or Raid 6 config /pool).

I appreciate that the information below would normally be something a Solutions Architect would  advise upon, but struggling to obtain that feedback through our VAR or  HP Account manager so would grateful if someone could recommend the no and qty of disks required. I should add that the x3 Servers (and associated MSA2052's) would be mostly hosting static data (and would at most, only be supporting 3-4 users). As a result, performance should hopefully not need to be a factor in determining what disks we should use.

My initial thought is that if we used approx 16 -20 1.3TB 10k SFF/SAS disks with some faster 15k 600 SFF/SAS or 900GB SFF/SAS in the remaining (x4 ?) slots, that would be more than adequate to provide us with a large enough pool to easily accommodate (upto) 19 Virtual volumes sized below or is that way more storage than we would need ?. I understand that sparesets drives are no longer an option under MSA's so if possible would prefer to Thin provision under Raid 6, to give us a little more redundancy (assuming that our proposed configuration would allow) ?

[ArunKKR]

Hi,

I believe that there is a confusion regarding MSA virtual pool configuration and how it works.
MSA 2050 supports virtual pools - Pool A and Pool B.
All the disk groups created under controller A would be used to create Pool A.
Similarly all the disk groups created under controller B would be used to create Pool B.

A pool is an aggregation of one or more disk groups that serves as a container for volumes.
RAID is configured at the disk group level.
We could create multiple disk groups under a single Pool
Volumes do not fall directly under disk groups.
The volumes are carved out from the space in each pool.
Data in a volume is spread across the disk groups in a pool.
Unlike older version MSAs you would not be able to create a linear vdisk of RAID  type of your preference and create volume under the specific linear vdisk.
As per the table you would require total capacity of around 3.7TB for server 1 ,  4.5TB for server 2 and 3.9TB for server 3.
I believe that the 10k rpm disks that you are referring to has a capacity of 1.2TB.

Please confirm whether you are planning to use 3 X MSA 2050 arrays.
One MSA 2050 connected to each server.

Below recommendation is provided based on assumption that one MSA 2050 array attached to each server would be used (total of 3 X MSA 2050).
I am not really sure whether 3 X MSAs are needed as a single MSA should meet the space requirements for all the 3 servers.

If there are 3 X MSAs , 6 X 1.2TB SAS disks in RAID 6 disk group (in one MSA) would meet the space requirements of servers 1 and 3.
These disk groups meet power of 2 disk group recommendation for optimal performance.
For the server 3 , 7 X 1.2TB SAS disks in RAID  6 disk group would meet the space requirements. 
10 X 1.2TB SAS disks in RAID  6 disk group meets the power of 2 recommendation for optimal performance. However, you might be adding 3 drives extra to meet this recommendation. There is a significant sequential write performance improvement when disk groups are created by following power of 2 recommendation.

Please refer to pages 18 and 19 of MSA best practives guide for information on power of 2 recommendation:

https://www.hpe.com/psnow/doc/a00015961enw?jumpid=in_lit-psnow-red

For optimal write sequential performance, parity-based disk groups (RAID 5 and RAID 6) should be created with “the power of 2” method. This
method means that the number of data drives (nonparity) contained in a disk group should be a power of 2

Below recommendation is provided based on assumption that 1 X MSA 2050 array attached to 3 servers would be used.

Create 1 disk group (10 X 1.2TB SAS disks in RAID  6) under Pool A .
Create separate volumes for servers 1 , 2 in Pool A.
Create 1 disk group (6 X 1.2TB SAS disks in RAID  6) under Pool B .
Create volume under Pool B for server 3.

Please let me know whether this information helps.

[Paolo_c]

I'm very grateful for the information you've provided. With regards to your question below. As x3 the Servers will be located at separate sites we would be looking at connecting one MSA2050 to each Server. 

"Please confirm whether you are planning to use 3 X MSA 2050 arrays. One MSA 2050 connected to each server.? "

With regards to the your feedback below. I think you might be referring to Server 2 not 3 (as you make reference to Server 1 & 3 in preceding sentence )? 

"For the server 3 , 7 X 1.2TB SAS disks in RAID  6 disk group would meet the space requirements. "

With regards to the power of 2 disk group recommendation for optimal performance. Do you believe that 10k 1.2 TB would provide good enough performance under a single MSA2050 with x2 pool groups under separate controllers to spread the load or would we better of going for say 900GB 15k SAS drives instead ?

Attached is a performance screenshot from our existing 3PAR 8200 SSMC console showing Server 1 , Server 2 and Server 3  respectively. As you can see the iops for Server 1 especially for evening backups (and hourly snapshots) tends to spike a lot but, on average,  has a combined read/write IOPs of around 1500 on Server 1 and well below 500 IOPs average read/write on the other 2 Servers. Although I do expect the workload /userbase on Server 1 to decrease a little between now and the autumn migration (to the rx2800/msa2050's solution), i still think we can expect similar performance spikes going forward so wondering whether the 15k 900GB's would suit us better. (even if that involves purchasing more disks )  

[ArunKKR · Accepted solution]

Hi Paolo,

It would be better to use 900 GB 15K rpm drives for performance.

10 X 900 GB 15K rpm drives in RAID 6 disk group in each MSA should meet  the capacity requirements.
You would get a usable capacity of around 6.55 TiB with this configuration in each MSA.

This configuration should meet the performance requirements for servers 2 and 3. For server 1 the IOPS might be at the higher end with this configuration.

You might need to work with your account manager and storage consultant to get suggestions on configuration that meets your performance requirements as it involves a lot of factors and review of your environment.