From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dongjun Shin Subject: Re: ssd optimised mode Date: Mon, 23 Feb 2009 12:15:51 +0900 Message-ID: <7fe698080902221915w6f961227ub26abae7f57302ae@mail.gmail.com> References: <934e480c0902200326m7647d87cq28bfa1675ef012f4@mail.gmail.com> <20090220160134.GE24890@unused.rdu.redhat.com> <1235147425.13249.16.camel@think.oraclecorp.com> <3a7f57190902211707h37ff1478vdc0e5ffff66fa4da@mail.gmail.com> <49A18F01.3090300@austin.ibm.com> <3a7f57190902221706l34e8f925m9ef687c1df920123@mail.gmail.com> <7fe698080902221722q257819aaj4378dfc1509d3c7d@mail.gmail.com> <3a7f57190902221833i61beb82u38c29dda0eaf5f42@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: linux-btrfs@vger.kernel.org To: Dmitri Nikulin Return-path: In-Reply-To: <3a7f57190902221833i61beb82u38c29dda0eaf5f42@mail.gmail.com> List-ID: On Mon, Feb 23, 2009 at 11:33 AM, Dmitri Nikulin wrote: > On Mon, Feb 23, 2009 at 12:22 PM, Dongjun Shin wrote: >> A well-designed SSD should survive power cycling and should provide atomicity >> of flush operation regardless of the underlying flash operations. I don't expect >> that users of SSD have different requirements about atomicity. > > Well that's my point, it "should" provide atomicity, but is this the > case for consumer SSDs? It is certainly NOT the case for cheap > USB-based flash media and AFAIK not for CF either. > AFAIK, all enterprise and consumer SSDs have atomicity requirements because they're designed to replace the HDD without changes to the OS. USB or any kind of flash-based cards have different requirements. They're optimized for cost and the priority for the atomicity is low. Moreover, they can be plugged out without prior notice to OS. -- Dongjun