On Tue, May 25, 2010 at 01:52:47PM +0100, Karl Pielorz wrote: > > --On 25 May 2010 15:28 +0300 Pasi Kärkkäinen <pa...@iki.fi> wrote: > >>> I've tried contacting Intel to find out if it's true their "enterprise" >>> SSD has no cache protection on it, and what the effect of turning the >>> write cache off would have on both performance and write endurance, but >>> not heard anything back yet. >>> >> >> I guess the problem is not the cache by itself, but the fact that they >> ignore the CACHE FLUSH command.. and thus the non-battery-backed cache >> becomes a problem. > > The X25-E's do apparently honour the 'Disable Write Cache' command - > without write cache, there is no cache to flush - all data is written to > flash immediately - presumably before it's ACK'd to the host. > > I've seen a number of other sites do some testing with this - and found > that it 'works' (i.e. with write-cache enabled, you get nasty data loss > if the power is lost - with it disabled, it closes that window). But you > obviously take quite a sizeable performance hit. >
Yeah.. what I meant is: if you have write cache enabled, and the ssd drive honours 'CACHE FLUSH' command, then you should be safe.. Based on what I've understood the Intel SSDs ignore the CACHE FLUSH command, and thus it's not safe to run them with caches enabled.. > We've got an X25-E here which we intend to test for ourselves (wisely ;) > - to make sure that is the case... > Please let us know how it goes :) -- Pasi _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
