On Mon, 6 Aug 2012, Stefan Ring wrote:
Intel's brief also clears up a prior controversy of what types of
data are actually cached, per the brief it's both user and system
data!
So you're saying that SSDs don't generally flush data to stable medium
when instructed to? So data written before an fsync is not guaranteed
to be seen after a power-down?
If that -- ignoring cache flush requests -- is the whole reason why
SSDs are so fast, I'm glad I haven't got one yet.
Testing has shown that many SSDs do not flush the data prior to
claiming that they have done so. The flush request may hasten the
time until the next actual cache flush.
As far as I am aware, Intel does not sell any enterprise-class SSDs
even though they have sold some models with 'E' in the name. True
enterprise SSDs can cost 5-10X the price of larger consumer models.
A battery-backed RAM cache with Flash backup can be a whole lot faster
and still satisfy many users.
Bob
--
Bob Friesenhahn
bfrie...@simple.dallas.tx.us, 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
