Usually we do GB/$ when it comes to buy storage, we want storage space, huge storage space for less money… But sometime we need fast storage, read lots of IOPS, and then comes in the idea of IOPS/$. Usually we quote for 15K disk, in RAID1+0 for maximum performances. Such configurations cost a lot of money! Did you know that even thought SSD (Solid State Disk) are much expensive per gigabyte than a 15K, it is much cheaper when talking of IOPS/$.
Chad Sakac just posted a very interesting article on SSDs. He was a bit skeptical about this new technology but when looking at the figures, he changed his mind.
A 1.5TB 7200 SATA drive can be bought for $115. But it will do 80 4K random write IOps. So:
- Expressed as GB/$ = the SATA drive is a 38x better deal
- Expressed as IOps/$ = the SSD drive is a 50x better deal (for write IO workloads, for reads, it’s 93x better). The SSD delivers 34 IOps per dollar. The SATA drive deliver 0.69 IOps per dollar.
To match the random read IO performance of that $115 Solid State disk, you would need 50 of the 1.5TB SATA disks.
Another article, VMware vSphereTM 4 Clocks 364,000 IOPS in Record Storage Throughput, demonstrates the performances of SSD disks 6 months ago already.