fsck strangeness
Ian Smith
smithi at nimnet.asn.au
Thu Aug 23 10:57:32 PDT 2007
On Thu, 23 Aug 2007, CyberLeo Kitsana wrote:
> Ian Smith wrote:
> > My knowledge of this is thin, despite reading McKusick's paper through
> > several times, but we're told that background fsck runs on a snapshot of
> > the fs concerned. How any bg fsck corrections are woven back into the
> > live fs later is still a mystery to me, but that's because I still have
> > an only barely superficial understanding of how snapshots work ..
>
> Background FSCK only repairs a small subset of filesystem
> incosistencies. Specifically, those inconsistencies that softupdates
> allows to occur, such as data blocks allocated out of the bitmap, but
> not actually assigned to any inode. Background FSCK only needs to find
> these (by looking at a fully consistent and unchanging snapshot of the
> filesystem) and deallocate them in the live filesystem, a simple
> operation given that it's guaranteed nothing will be using a block that
> is both marked used and not assigned to anything.
Thanks for that nutshell, CL. Sometimes little bits help the most <&^}=
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