On 8/15/11 12:50 PM, David Magda wrote:
On Mon, August 15, 2011 12:25, Ray Van Dolson wrote:
On the Intel SSD 320 Series, the spare capacity reserved at the
factory is 7% to 11% (depending on the SKU) of the full NAND
capacity. For better random write performance and endurance, the
spare capacity can be increased by reducing the usable capacity of
the drive; this process is called over-provisioning.
So this is hard-coded at the factory, and one must 'decode' the SKU to
determine how much is set aside? Are the different SKU's values documented
somewhere?
Usually you can guess, given that there are 10 channels and flash chips
are powers of two: the 80 GB model has 80 GiB of flash, the 300 GB model
has 320 GiB, etc. Apparently the 120 GB model has something like 137 GB
(?!), though. If you really want to know for sure you can find a
teardown on the Web.
You can then over-over-provision down to any size you want by setting
the HPA (I've only done this under Linux using hdparm; not sure how it's
done in Solaris).
Wes Felter
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