Solid State Hard Drives

Here are my thoughts on solid state hard drives.

In our world of information in their care, we are always looking for the next thing "big". It is often a new chip from Intel or AMD. However, in recent years, the microprocessor is not usually the limiting factor in computer performance.

Although the capacity of hard disk storage has increased significantly in recent years has remained relatively constant speed access. It is a question / problem is fundamental to technology. The hard drive is mechanical, and efforts to improve the speed have been diminishing returns.

A technology that competes with traditional hard disk drive (HDD) is the solid state drive (SSD). A SSD is not mechanically, based on the "flash memory", the same chip technology used to store pictures with your digital camera. A new SSD drive is only 3 years but not more.

An SSD can overcome conventional mechanical hard drives, because the 4X smaller and lighter, it is up to 50 times faster and is more reliable because there are no moving parts, produces less heat and consumes less energy. Disk capacity has improved SSD memory and 250 GB SSDs are now available. Currently, the disadvantage is the price.

SSDs are more expensive than conventional hard disk. An SSD drive now costs about $ 2 per gigabyte, while hard drive costs less than $ 1 per gigabyte. The price of one continues to improve SSD (SSD drives, once sold for more than $ 25 per gigabyte), and the anticipated volume of production, the price difference should be further reduced.

Flash memory is capable of a finite number of rewrites each memory cell (as conventional hard disks). Significant improvements in technology have emerged in recent years. In addition, Intel developed the "load leveling". This technique ensures that all memory cells in the SSD to receive a similar workload. Most SSD manufacturers are now using similar techniques. An SSD should last 10 years or more for the average user.

The main reason for the promising future of SSD is the access speed. A conventional hard drive has a fast access time equal to approximately 5 milliseconds. It sounds fast, but when the microprocessor is capable of millions of instructions per second (MIPS), 5 milliseconds is a bottleneck. SSD may have as few as 100 microsecond access time (50 times faster).

An important question when trying to use this capacity SSD speed is the potential bottleneck caused by the interface. There are 3 common interfaces used today with SSD.

The SATA interface is currently the most common interface used in conventional hard disk, but a SATA interface is limited in the total return, send and receive about 3 Gbps. This may be slow to SSD, which failures in performance. Some units are suitable for SSD performance of more than 5 Gbps.

Seagate Technology, in collaboration with AMD, has recently announced the Serial ATA storage interface for 6-Gbps SATA also called version 3.0, a next-generation technology capable of twice the speed of the faster SATA interface available today. This technology was demonstrated by conventional hard drives, but has an obvious application for the SSD market.

SAS (Serial Attached SCSI) is an alternative interface. SAS is a point in the technology by at least four channels. Each channel is capable of the performance of 3 Gb / s each way (total of 6 Gb / s per channel).

A third alternative is to use the SSD with PCI Express interface. A PCI Express interface with unidirectional data paths, and you receive is sent, each at 2.5 Gbps to 5 Gbps performance.

You can maximize the performance benefits of SSD technology with a careful selection of the appropriate interface.