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Solid State Drives; future of the hard disk

meet the future of hard disk drives the SSD or Solid State Drives

Nowdays you have heard about the SSD or Solid State Drives, what is a solid state drive? well it seems solid state drives may replace the long popular and viable mechanical Hard Disk as we know today.  solid state drives are what you see now are our flash drives and USB storage devices, but ssds are larger and has more capacity and speed, the first true SSDs are industrial grade flash medias used by large industries and internet firms. it is also macintosh's secret in their products since the launch of the Mac OSX series. 

comparison of an ordinary hard disk to a SSD hard disk

Principle of  Solid State Drives:

The principle behind solid state drives is that there should be no moving parts: no spinning platters, no moving heads. Data is split into word length pieces and stored in memory. It is then accessed almost instantaneously using unique system-wide addresses. This behaviour has been used in computer RAM for many years, but for a long time it was too expensive for manufacturers to consider using it as persistent storage in sufficient volumes to replace the hard disk drive.

Solid state disks use either NAND flash or SDRAM (non-volatile and volatile storage respectively). NAND flash is so-called because of the NAND-gate technology it uses and is common in USB flash drives and many types of memory card. NAND flash based drives are persistent and can therefore effectively mimic a hard disk drive. Synchronous dynamic random access memory (SDRAM) is volatile and requires a separate power source if it is to operate independently from a computer.

Solid state drives may be preferred over traditional disk drives for a number of reasons. The first advantage is found, as mentioned briefly above, in the speed of operation. Because hard disk drives need to be spinning for the head to read sectors of the platter, sometimes we have to wait for "spin up" time. Once the disk is spinning, the head must seek the correct place on the disk, and from there the disk must spin just enough so that the correct data is read. If data is spread over different parts of the disk (fragmented) then this operation is repeated until all the data has been read or written. While each individual operation only takes fractions of a second the sum of them may not. It is often the case that reads to and writes from the hard disk are the bottleneck in a system.

Because the information on solid state drives can be accessed immediately (technically at the speed of light) there is no latency experience when data is transferred. Because there is no relationship between spatial locality and retrieval speed, there is no degradation of performance when data is fragmented.

Consequences of the increased speed of writes for fragmented data include a much decreased application start up time: SanDisk, for instance, claim to have achieved Windows Vista start up times of around 30 seconds for a laptop with its SSD SATA 5000 2.5".

Solid state drives also enjoy greater stability over their disk counterparts. Because there are no moving parts there is less that can go wrong mechanically. Dust entering the device ceases to become a problem (and in any case solid state drives can be sealed air tight unlike disk drives which require a certain air cushion to function properly), and dropping the drive is less likely to cause damage to the data. There are no heads so head crashes are a thing of the past.

according to wikipedia, here are some pros and cons of SSDs:


- Faster start-up because no spin-up is required.
- Fast random access because there is no read/write head
- Low read latency times for RAM drives. In applications where hard disk seeks are the limiting factor, this results in faster boot and application launch times (see Amdahl's law).
- Consistent read performance because physical location of data is irrelevant for SSDs.
- File fragmentation has negligible effect.
- Silent operation due to the lack of moving parts.
- Low capacity flash SSDs have a low power consumption and generate little heat when in use.
- High mechanical reliability, as the lack of moving parts almost eliminates the risk of "mechanical" failure.
- Ability to endure extreme shock, high altitude, vibration and extremes of temperature. This makes SSDs useful for laptops, mobile computers, and devices that operate in extreme conditions (flash).
- For low-capacity SSDs, lower weight and size: although size and weight per unit storage are still better for traditional hard drives, and microdrives allow up to 20 GB storage in a CompactFlash form-factor. As of 2008 SSDs up to 256 GB are lighter than hard drives of the same capacity.
- Flash SSD's have twice the data density of HDD's (so far, with very recent and major developments of improving SSD densities), even up to 1TB disks (currently more than 2TB is atypical even for HDD's). One example of this advantage is that portable devices such as a smartphone may hold as much as a typical person's desktop PC.
- Failures occur less frequently while writing/erasing data, which means there is a lower chance of irrecoverable data damage.


  • Wear leveling used on flash-based SSDs has security implications. For example, encryption of existing unencrypted data on flash-based SSDs cannot be performed securely due to the fact that wear leveling causes new encrypted drive sectors to be written to a physical location different from their original location -- data remains unencrypted in the original physical location. It is also impossible to securely wipe files by overwriting their content on flash-based SSDs.
  • As of early-2010, SSDs are still more expensive per gigabyte than hard drives. Whereas a normal flash drive is US$2 per gigabyte, hard drives are around US$0.10 per gigabyte for 3.5", or US$0.20 for 2.5".
  • The capacity of SSDs is currently lower than that of hard drives. However, flash SSD capacity is predicted to increase rapidly, with drives of 1 TB already released for enterprise and industrial applications.
  • Asymmetric read vs. write performance can cause problems with certain functions where the read and write operations are expected to be completed in a similar timeframe. SSDs currently have a much slower write performance compared to their read performance.
  • Similarly, SSD write performance is significantly impacted by the availability of free, programmable blocks. Previously written data blocks that are no longer in use can be reclaimed by TRIM; however, even with TRIM, fewer free, programmable blocks translates into reduced performance.
  • Flash-memory drives have limited lifetimes and will often wear out after 1,000,000 to 2,000,000 write cycles (1,000 to 10,000 per cell) for MLC, and up to 5,000,000 write cycles (100,000 per cell) for SLC. Special file systems or firmware designs can mitigate this problem by spreading writes over the entire device, called wear leveling.
  • As a result of wear leveling and write combining, the performance of SSDs degrades with use.
  • SATA-based SSDs generally exhibit much slower write speeds. As erase blocks on flash-based SSDs generally are quite large (e.g. 0.5 - 1 megabyte),[8] they are far slower than conventional disks during small writes (write amplification effect) and can suffer from write fragmentation. Modern PCIe SSDs however have much faster write speeds than previously available.
  • DRAM-based SSDs (but not flash-based SSDs) require more power than hard disks, when operating; they still use power when the computer is turned off, while hard disks do not.
  • Defragmentation cannot be performed on flash-based SSDs due to wear leveling (operating system cannot control the real physical location of disk sectors). Some SSDs compact free space when idle. However, this improves only writing speed -- not reading speed of existing fragmented data.

A gigabyte 80gb SSD module

availability sa Pinas:

although some people here have their hands on SSD and Similar devices, SSDs are only available as of now in the local market in mac pc's and similar products. maybe two years from now, the SSD drives is available...

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