Date: Mon, 31 Mar 2008 22:23:37 +0000 From: "Poul-Henning Kamp" <phk@phk.freebsd.dk> To: Bakul Shah <bakul@bitblocks.com> Cc: Christopher Arnold <chris@arnold.se>, Martin Fouts <mfouts@danger.com>, arch@freebsd.org, qpadla@gmail.com, freebsd-arch@freebsd.org Subject: Re: Flash disks and FFS layout heuristics Message-ID: <26080.1207002217@critter.freebsd.dk> In-Reply-To: Your message of "Mon, 31 Mar 2008 15:21:54 MST." <20080331222154.C976C5B50@mail.bitblocks.com>
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In message <20080331222154.C976C5B50@mail.bitblocks.com>, Bakul Shah writes: >On Mon, 31 Mar 2008 13:06:10 PDT Matthew Dillon <dillon@apollo.backplane.com> wrote: >> But how do you index that information? You can't simply append the >> information to the NAND unless you also have a way to access it. So >> does the filesystem have to scan the NAND (or significant portions of it) >> in order to build an index of the filesystem topology in system memory? > >One possible way: > >I'd design the system so that each update ends with the write >of a root block[1]. This is sort of the approach Margo Seltzer used for her (Kludge-)LFS it has many drawbacks, in particular when it comes to recovery. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.
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