Many of our customers have questions about adding or changing drives in their servers to get better performance. Here are some solutions xByte Technologies recommended recently when a customer running VMware, with a 720xd 24 bay server/4x 1.2TB 10K SAS drives/RAID 5, inquired about changing their SAS drives to SSDs without impacting their normal operation.
It can definitely be done, and there are several different options that will help increase IOPS:
A. Create a new disk array with 6x 800GB Mixed Use (MU) MLC SATA SSDs which gives you the same amount of raw space as the 4x 1.2TB 10K SAS drives. This would be the most cost effective way to attain better IOPS using all MU SSDs at $599 ea. per disk. After you created the new array you can simply migrate the data over to the SSDs.
B. If your workloads are more on the read intensive (RI) side than you can go with RI drives at $399 ea (same capacity). You want to make sure you get the correct SSDs for your workloads so you do not experience any latency.
C. Since RAID 5 is not a nested RAID level you can expand the existing array with more of the same 10K drives. The more spindles in an array the better the IOPS. Your R720xd has 24 drive bays and if you still only have the 4 drives we included you have plenty of space to add more. The same 1.2TB 10K SAS drives are $289 ea. If you add 4 more of these you can not only double your IOPS, but, also, your storage space.
D. You can throw in a couple of small SSDs and enable Cache Cade. This can increase IOPS by up to 75%.
Depending on what kind of performance you’d like to see and how much the budget allows will ultimately play a factor on deciding which upgrade method is best for you. To make it easier I would recommend running Dell’s DPACK tool to see where your latencies/bottlenecks are and get a good idea of where you really should be in terms of IOPS.
Guest Post: xByte Rep, Ernesto Sanchez