How Windows 7 will accelerate DSSS (direct sequence spread spectrum)

Currently, even if the DSS are very efficient, operating systems have a big problem: they use these storage systems based on flash memory as a hard disk. With Windows 7 and the latest version of the ATA standard, it will be different and the system could be optimized for SSD (or rather it will use a DSS correctly).

In the standard ATA-8

In the standard ATA-8 (version 7 is the most commonly used), the management of DSS is provided: a storage system can send to its speed and if it is 0, it was dealing with a SSD ( which, remember, has no moving parts). The first thing that is set up is simple: automatic defragmentation is disabled, this function has no effect on SSD (it is scheduled for devices to access time variable) and can pose problems of life (the entries in a DSS is limited).

Another interesting point, the SSD can also send the OS to the size of the blocks and its pages, which vary, which will enable the system to optimize the file system to avoid unnecessary paperwork aligning clusters on block size of flash memory.

The trim, or how DSS and OS must be understood


The novelty comes from the trims, a feature that will allow the OS to help the DSS to optimizer. Simplifying the current DSSs use management wear is called Static Wear Leveling. The controller DSS will try, with this technique to obtain a constant wear of the media, the operation is quite specific. When the system wants to write, the DSS will seek the best place to put up either an empty cell (which was never written) or, if none is available empty cell, the cell less worn DSS.

We understand quite easily that the empty cells are rapidly becoming a rare classic in use. In the (current) of cell less worn DSS, there are two possibilities: either the controller realized that the cell is often used (by writing meters) and is seeking another cell little worn, or he realizes that the cell is rarely used.

This case, which is optimized by the trims: rarely used a cell can contain two types of data, fixed data (the level of a game, for example) or data erased by the operating system (the filesystems conventional offset data not physically). And firmware DSS since it is independent of file system, can not know if it is a useful or not, and will perform a write operation: the contents of the cell will be used just transferred worn to a cell and write the data will be entered on the worn little cell that has just been released.

The trims are involved on this point: Windows 7, the file system (NTFS) can indicate when a file is deleted with a flag that includes the DSS. If the cell contains selected really an important, normal operation is in place, if the data is erased (for the file system), the DSS will write directly on the cell. In fact, instead of two entries and a cell search, we are left with only one writing. And because the writing is the weak point of the DSS, the gain can be interesting, especially if the DSS is widely used.

Note that (with the beta version of Windows 7), there aa priori no SSD compatible with this technology, but it looks promising. Hopefully, some manufacturers offer firmware adapted in the future, but nothing is less certain.