On Wed, 10 Sep 2008, Al Hopper wrote: > Interesting flash technology overview and SSD review here: > > http://www.anandtech.com/cpuchipsets/intel/showdoc.aspx?i=3403 > and another review here: > http://www.tomshardware.com/reviews/Intel-x25-m-SSD,2012.html
These seem like regurgitations of the same marketing drivel that you notified us about before. These Intel products are assembled in China based on non-Intel FLASH components (from Micron). There is little reason to believe that Intel will "corner the market" due to having an aggressive marketing department. There are other companies in the business who may seem oddly silent compared with Intel/Micron, but enjoy a vastly larger share of the FLASH market. These reviews continue their apples/oranges comparison by comparing cheap lowest-grade desktop/laptop drives with the expensive Intel SSD drives. The hard drive performance specified is for low-grade consumer drives rather than enterprise drives. The hard drive reliability specified is for low-grade consumer drives rather than enterprise drives. The table at Tom's Hardware talks about 160GB SSD drives which are not even announced. The SLC storage sizes are still quite tiny. The wear leveling algorithm ensures that the drive starts losing its memory in all locations at about the same time. RAID does not really help much here for reliability since RAID systems are usually comprised of the same devices installed at the same time and seeing identical write activity. RAID works due to failures being random. If the failures are not random (i.e. all drives start reporting read errors at once) then RAID does not really help. Hopefully the integration with the OS is sufficient that the user knows it is time to change out the drive before it is too late to salvage the data. Write performance to SSDs is not all it is cracked up to be. Buried in the AnandTech writeup, there is mention that while 4K can be written at once, 512KB needs to be erased at once. This means that write performance to an empty device will seem initially pretty good, but then it will start to suffer as 512KB regions need to be erased to make space for more writes. ZFS's COW scheme will intially be fast, but then the writes will slow after all blocks on the device have been written to before. Since writing to a used drive incurs additional latency, the device will need to buffer writes in RAM so that it returns to the user faster. This may increase the chance of data loss due to power failure. Bob ====================================== Bob Friesenhahn [EMAIL PROTECTED], http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
