cegras
02-21-2009, 09:42 AM
http://www.pcper.com/article.php?aid=669&type=expert&pid=1
Write combining sounds like a great idea on the surface, but things that seem too good to be true normally are, and there is no free lunch here either.
Since the flash locations are isolated from the OS by a lookup table, these fragments can not (presently) be directly manipulated by the OS, leaving any defragmentation efforts to the SSD itself. These fragmented areas will remain until they are overwritten by larger contiguous files. The end result is that the drive is not so much ‘adapting’ as it is approaching a steady state level of internal fragmentation as a result of the mix of small / large files being written to it. When we put the screws to the X25-M in the lab, we found that a ‘used’ X25-M will always perform worse than a ‘new’ one, regardless of any adaptive algorithms that may be at play. We also found that in some cases, the drive would drop to significantly below manufacturer specs.
If after reading this you quickly ran some benches on your own X25-M and found yourself in the ‘slowness’ category, you should realize there are ways to recover. We will attempt these by following Intel’s own advice on the matter, exploring two of their suggested methods.
Write combining sounds like a great idea on the surface, but things that seem too good to be true normally are, and there is no free lunch here either.
Since the flash locations are isolated from the OS by a lookup table, these fragments can not (presently) be directly manipulated by the OS, leaving any defragmentation efforts to the SSD itself. These fragmented areas will remain until they are overwritten by larger contiguous files. The end result is that the drive is not so much ‘adapting’ as it is approaching a steady state level of internal fragmentation as a result of the mix of small / large files being written to it. When we put the screws to the X25-M in the lab, we found that a ‘used’ X25-M will always perform worse than a ‘new’ one, regardless of any adaptive algorithms that may be at play. We also found that in some cases, the drive would drop to significantly below manufacturer specs.
If after reading this you quickly ran some benches on your own X25-M and found yourself in the ‘slowness’ category, you should realize there are ways to recover. We will attempt these by following Intel’s own advice on the matter, exploring two of their suggested methods.