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Wear Leveling, RAID Can Wipe Out SSD Advantage
storagedude writes "This article discusses using solid state disks in enterprise storage networks. A couple of problems noted by the author: wear leveling can eat up most of a drive's bandwidth and make write performance no faster than a hard drive, and using SSDs with RAID controllers brings up its own set of problems. 'Even the highest-performance RAID controllers today cannot support the IOPS of just three of the fastest SSDs. I am not talking about a disk tray; I am talking about the whole RAID controller. If you want full performance of expensive SSDs, you need to take your $50,000 or $100,000 RAID controller and not overpopulate it with too many drives. In fact, most vendors today have between 16 and 60 drives in a disk tray and you cannot even populate a whole tray. Add to this that some RAID vendor's disk trays are only designed for the performance of disk drives and you might find that you need a disk tray per SSD drive at a huge cost.'"
Sure, but why do you put 60 drives in a RAID?
Because hard disks, even the high end ones, have quite low IOPS. You can attain the same performance level with much fewer SSDs. If what you need is IOPS and not lots of storage that's a good thing even. You reach the required level with much fewer drives, so you need less power, less space and less cooling.