SSD's are flash based drives (a more advanced version of the one you might find in a digital camera) connected to SATA interfaces. There are no moving parts and hence are faster than HDD's but slower than RAM. SSD's fit in the middle and have benefits of both.
SSD's have very low seek time (no moving parts), the amount of time it takes to go find the data on the storage media. This is what gives them the edge over HDD's, but they are still connected to a SATA interface, limiting it to the same throughput as a SATA HDD. SSD's are especially great for random IO.
There are two kinds of SSD's: SLC and MLC. SLC is a single-cell, storing 1 bit in each memory cell. MLC is a multilevel cell, storing 2 or 3 bits in a cell. MLC's have more capacity but the catch is: SSD's are generally slower at writes, they need to clear the cells (pages) before writing to it. It is a two step process for writes.
SSD's prices are dropping a lot. Expect to see more of them in the coming years. They also save on power and are great for laptops!
In servers, and especially ZFS file systems, SSD's come especially handy.
0 Responses to Solid State Disks, a premier