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October 4th, 2011 17:00

Storage tiering with SAS/SATA drives with new EqualLogic 5.1 firmware

What are the recommendations for storage pools with the new EqualLogic 5.1 firmware? The old recommendation was to not mix drive types into the same pool with the same RAID policy. Now that the 5.1 firmware is out and it does sub volume tiering, what are the recommendations? I currently have a group with two PS400E members both using RAID 50 in the default pool. I am adding a PS4100X RAID 50, and one of the PS400E members will be removed. So, should I put the 4100X into the default pool and let the group figure out how to distribute the data using enhanced load balancing, or do I need to put the PS4100X into a different pool and then assign my volumes to a specific pool? I have only found a very brief mention of the enhanced load balancing in the 5.1 release notes.

7 Technologist

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729 Posts

October 5th, 2011 05:00

khsieh,

Yes, the new improvements to the Performance Load Balancing in v5.1.x and the sub-volume tiering performance balancing capabilities now allow for mixed drive technologies and mixed RAID policies coexisting in the same storage pool.

In your case, you would have mixed drive technologies (the PS400E, SATA 5k and the PS4100X, SAS 10k) with each member running the same RAID policies.

When the PS4100X is added to the pool, normal volume load balancing will take the existing volumes on the two PS400X’s and balance them onto the PS4100X. Once the balancing is complete and you then remove the PS400E from the group, the volumes slices contained on this member will be moved to the remaining two members and be balanced across both members (the SATA and SAS) at that point.

Note, however, that Sub-volume performance load balancing may not be so noticeable until the mixed pools experience workloads that show tiering and are regular in their operating behavior. Because the operation takes place gradually, this could take weeks/months depending on your specific data usage.

For additional information:
http://content.dell.com/us/en/enterprise/d/business~solutions~power~en/Documents~ps3q11-20110327-chadran.pdf.aspx .

Regards,
Joe

1 Rookie

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14 Posts

October 5th, 2011 12:00

Thanks for the article link. Is there a technical document that would describe more of the ins and outs of how one might want to configure the group, different caveats and situations where putting everything into a single pool might be better or worse than the traditional tiering, and other implementation considerations? The document gave a reasonable technical overview, but I wouldn't describe it as having the amount of technical detail required for solid implementation. I don't even know if it is something that can be turned on and off.

7 Technologist

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729 Posts

October 6th, 2011 04:00

khsieh,

The technical document we have on the Load Balancers is: "TR1070 - EqualLogic PS Series Architecture - Load Balancers.pdf". It is available on the support site at this link: https://support.equallogic.com/support/tech_reports.aspx (login required). Once on that page, search for Load balancers and you should see the titile: "EqualLogic PS Series Architecture - Load Balancers".

Regards,
Joe
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