SSD IOPS: Important metrics to consider

Besides price per gigabyte, what other metrics should be weighed when considering SSDs?

Two important metrics that have not been examined until recently are price per IOPS and IOPS per watt of electric power. These are measures of performance and efficiency, which are becoming increasingly important. SSD IOPS are much higher than HDD IOPS. Generally speaking, SSDs range from $0.004 to $0.15 per IOPS and HDDs range from $1 to $4 per IOPS. SSDs vary from 1,000 to 15,000 IOPS per watt and HDDs vary from 10 to 40 IOPS per watt. My general statement is that SSDs are dollars per gigabyte and pennies per IOPS, while HDDs are pennies per gigabyte and dollars per IOPS.