On 2/2/2012 5:19 PM, Peter A wrote: > On 02/02/12 17:01, William Warren wrote: >> On 2/2/2012 2:15 PM, Peter A wrote: >>> If you're worried about io reliability, then buy a (way more expensive) >>> SLC drive, rather than the consumer level MLC... We have some SLC drives >>> here that from their manufacturer have been rated at 3 or more years of >>> 100% write 24x7... >>> >>> Peter. >>> >>> _______________________________________________ >>> CentOS mailing list >>> CentOS at centos.org >>> http://lists.centos.org/mailman/listinfo/centos >> exactly hence why i said stay with OCZ or Intel..MLC drives are the >> best. But also the smaller the process node the shorter the lifespan of >> the flash. MLC drives will also over provision more spare flash area >> most times. > Aeh... that's exactly the opposite of what I said. MLC (multi level > cell) SSDs store more than one bit per cell. In current devices that's > mostly 2 bits per cell, but more is around the corner. On an SLC (single > level cell) there is only one bit per cell - true binary just like what > we have in RAM and others. SLC devices are superior in reliability > because it simply takes a lot more disturbing of a cell to make it lose > enough charge that a 1 gets interpreted as a 0. The devices are also > usually faster, especially on a re-write basis. > A Oracle 96GB flash card (SLC) physically has 128GB. Most consumer MLC > devices with 128GB are sold as 120GB visible... Again in favor of the > SLC. Only problem is that you pay for what you get. SLC devices are > significantly more expensive. Fusion I/O and all the other server ssd > vendors do the same - they give you a cheap MLC device with limited > performance and reliability and a high end, much more pricey SLC unit. > > Peter. > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos i mistyped meant to type slc...:)