From EZP Knowledge Base

SSD stands for Solid State Device. SSD's come in many different variations - from the cheap and slow SDHC card in your camera that uses NAND Flash memory to extremely expensive DRAM based devices built on the same technology as the RAM/Memory modules in your PC are. Then there are the drives that use NAND Flash memory but have a fast controller, a hard drive interface (EIDE or SATA typically) and come in standard hard drive sizes of 1.8", 2.5" or 3.5". When referring to SSD's, we typically are referring to this last category of drives.

These SSD's have many advantages over traditional hard drives. In a traditional hard drive you have a platter that holds your data and spins around at high speeds. When you require data off the drive, the platter must spin up and the head must find the data, this is called seek or access time. For a really simplified example, think of a record on a record player - to play a song you need to put the needle (the head) on the record (the platter) in the right spot.

An SSD has no moving parts and thus seek times are an almost instantaneous 0.1ms compared to a standard mechanical hard drive, where *fast* seek times are around 5.0ms. A typical SATA drive has seek times of around 7-9ms. Seek times are very important - to us 5.0ms seems instant, but to a CPU in a modern PC or Server 5ms is a lot of time wasted.

While seek times is where SSD's really shine, surprisingly they are also faster then a traditional hard drive in other area's - namely the speed at which the SSD can send data off the drive, also known as Read speed. The fastest mechanical SATA drive on the market right now is the Western Digital Velociraptor. Using Bonnie++, a benchmarking utility; the Velociraptor has an average Read speed of 85MB/s. This is fast. However, in our testing of multiple SSD's we have seen read speeds of between 150-240MB/s on the same benchmarking utility.

There are some things to be concerned about with SSD's. Typically, an SSD has a slower Write speed (how fast data can be written to the drive) then mechanical SATA drives. Write speed is very important, especially in a Webhosting Server environment. Using Bonnie++ the Velociraptor gives an average Write speed of 70MB/s. Most of the SSD's on the market will give a result of between 20-45MB/s for write speed.

At EZP, we've found a method to increase Write speeds on SSD's to between 85-110MB/s!

The other big concern regarding SSD's is that they have a finite lifespan - you can only write so much data to NAND chips before they start to give incorrect/corrupt data when read. This is due to the limited number of write or erase cycles inherent in NAND flash. MLC based SSD's have a limit of approximately 10,000 erase cycles while the more expense SLC devices have approximately 100,000 erase cycles. This is devastating in a server environment, as an MLC device would likely last under a year, while and SLC device would likely last only a few years. A traditional hard drive can last the life of the server.

With the same method EZP uses to increase Write speeds on SSD's, we also get the added benefit of prolonging the life of SSD's by a factor of up to 50!

Finally, SSD's use less power and thus generate less heat then a traditional drive.