[CentOS] SSD Drives

[William Warren]

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.
>>>
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>> 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.
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i mistyped meant to type slc...:)