On Sat, 24 Oct 2009, Bob Friesenhahn wrote:
Is solaris incapable of issuing a SATA command FLUSH CACHE EXT?
It issues one for each update to the intent log.
I should mention that FLASH SSDs without a capacitor/battery-backed
cache flush (like the X25-E) are likely to get burned out pretty
quickly if they respect each cache flush request. The reason is that
each write needs to update a full FLASH metablock. This means that a
small 4K syncronous update forces a write of a full FLASH metablock in
the X25-E. I don't know the size of the FLASH metablock in the X25-E
(seems to be a closely-held secret), but perhaps it is 128K, 256K, or
512K.
The rumor that disabling the "cache" on the X25-E disables the wear
leveling is probably incorrect. It is much more likely that disabling
the "cache" causes each write to erase and write a full FLASH
metablock (known as "write amplification"), therefore causing the
device to wear out much more quickly than if it deferred writes.
http://www.tomshardware.com/reviews/Intel-x25-m-SSD,2012-5.html
Bob
--
Bob Friesenhahn
bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
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