Messages in this thread | | | Date | Thu, 04 Sep 2003 22:37:10 +0400 | From | Hans Reiser <> | Subject | Re: precise characterization of ext3 atomicity |
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Mike Fedyk wrote:
>On Thu, Sep 04, 2003 at 08:25:18PM +0400, Hans Reiser wrote: > > >>In data=journal and data=ordered modes ext3 also guarantees that the >>metadata will be committed atomically with the data they point to. However >>ext3 does not provide user data atomicity guarantees beyond the scope of a >>single filesystem disk block (usually 4 kilobytes). If a single write() >>spans two disk blocks it is possible that a crash partway through the write >>will result in only one of those blocks appearing in the file after >>recovery. >> >> > >And how does reiser4 do this without changing the userspace apps? > We don't. We just make the hovercraft, we don't force you to go over the water.....
> >Most files are written with several write() calls, so even if each call is >atomic, your entire file will not be there. > >Also, ext3 could claim the same atomicity if it only updated meta-data on >write() call boundaries, instead of block boundaries. > > > >
-- Hans
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