Date: Tue, 30 Oct 2001 11:17:49 -0800 (PST) From: Julian Elischer <julian@elischer.org> To: Bruce Evans <bde@zeta.org.au> Cc: Alexander Leidinger <Alexander@leidinger.net>, fs@FreeBSD.ORG Subject: Re: physical block no -> name of file (FFS)? Message-ID: <Pine.BSF.4.21.0110301117270.26174-100000@InterJet.elischer.org> In-Reply-To: <20011031044552.U4473-100000@delplex.bde.org>
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Bruce, they already KNOW the bad block address. they want to find what file it is in... On Wed, 31 Oct 2001, Bruce Evans wrote: > On Tue, 30 Oct 2001, Alexander Leidinger wrote: > > > On 30 Okt, Bruce Evans wrote: > > > Just back up the files and note which ones can't be read. Better, compare > > > them with a previous backup. > > > > Yes, this solves my problem (now that I know in which partition the bad > > block is). > > > > But doesn't this need more resources than a dedicated program which only > > traverses the metadata? On a busy system it may be worthwile to have > > such a program (and I may be willing to write it). > > It is not possible to detect unreadable files by traversing only their > metadata. Only unreadable metadata may be detected in this way. Every > block in every file must be read to see if it can be, erm, read. It > may be possible to find them all using dd on the disk device (with a > block size of 1b so as not to miss any), but if there are a lot of > them this probably won't be much faster than reading the files, > especially if not all the bad blocks are in files, since the time for > retrying the reads will dominate. > > > >> But thanks for the hint, I haven't thought at looking into fsck, will do > > >> it later. > > > > > > fsck is not very useful for the original problem of finding files with > > > bad blocks in them, since it only accesses metadata. > > > > And the sequence of blocks which holds the content of a given file > > isn't included in this metadata? > > You still have to read them all to see if they are bad. The filesystem > is likely to be better optimized for doing this than any simple program. > > Bruce > > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
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