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To: Bakul Shah <bakul@bitblocks.com>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Mon, 31 Mar 2008 15:21:54 MST."
	<20080331222154.C976C5B50@mail.bitblocks.com> 
Date: Mon, 31 Mar 2008 22:23:37 +0000
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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 
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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.