From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.tmr.com ([64.65.253.246] helo=gaimboi.tmr.com) by canuck.infradead.org with esmtps (Exim 4.63 #1 (Red Hat Linux)) id 1HpQhv-0007rr-Vu for linux-mtd@lists.infradead.org; Sat, 19 May 2007 11:19:02 -0400 Message-ID: <464F1539.5050204@tmr.com> Date: Sat, 19 May 2007 11:18:17 -0400 From: Bill Davidsen MIME-Version: 1.0 To: Dongjun Shin Subject: Re: [PATCH] LogFS take three References: <20070515151919.GA32510@lazybastard.org> <20070515133759.9ee434a2.akpm@linux-foundation.org> <1179317240.2859.222.camel@shinybook.infradead.org> <20070516083408.dcd9dd78.akpm@linux-foundation.org> <1179330596.2859.248.camel@shinybook.infradead.org> <20070516164158.GB8113@lazybastard.org> <7fe698080705162312t4e7ed90byd10ef8e664027b17@mail.gmail.com> <1179383117.2859.416.camel@shinybook.infradead.org> <7fe698080705170120w18fe5521oa685cf248a45e1c6@mail.gmail.com> In-Reply-To: <7fe698080705170120w18fe5521oa685cf248a45e1c6@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Evgeniy Polyakov , Albert Cahalan , Greg KH , =?ISO-8859-1?Q?J=F6rn_Engel?= , linux-kernel@vger.kernel.org, Ingo Oeser , Pekka Enberg , linux-mtd@lists.infradead.org, Jan Engelhardt , linux-fsdevel@vger.kernel.org, Andrew Morton , David Woodhouse , Thomas Gleixner List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Dongjun Shin wrote: > There are so many flash-based storage and some disposable storages, > as you pointed out, have poor quality. I think it's mainly because these > are not designed for good quality, but for lowering the price. > The reliability seems to be appropriate to the common use. I'm doubious that computer storage was a big design factor until the last few years. A good argument for buying large sizes, they are more likely to be recent design. > These kind of devices are not ready for things like power failure because > their use case is far from that. For example, removing flash card > while taking pictures using digital camera is not a common use case. > (there should be a written notice that this kind of action is against > the warranty) > They do well in such use, if you equate battery death to pulling the card (it may not be). I have tested that feature and not had a failure of any but the last item. Clearly not recommended, but sometimes unplanned needs arise. > - In contrast to the embedded environment where CPU and flash is directly > connected, the I/O path between CPU and flash in PC environment is longer. > The latency for SW handshaking between CPU and flash will also be longer, > which would make the performance optimization harder. > > As I mentioned, some techniques like log-structured filesystem could > perform generally better on any kind of flash-based storage with FTL. > Although there are many kinds of FTL, it is commonly true that > it performs well under workload where sequential write is dominant. > > I also expect that FTL for PC environment will have better quality spec > than the disposable storage. The recent technology announcements from Intel are encouraging in that respect. -- Bill Davidsen "We have more to fear from the bungling of the incompetent than from the machinations of the wicked." - from Slashdot