Messages in this thread | ![/](/images/icornerl.gif) | | Date | Fri, 05 Sep 2003 01:03:03 +0400 | From | Hans Reiser <> | Subject | Re: precise characterization of ext3 atomicity |
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Mike Fedyk wrote:
>On Thu, Sep 04, 2003 at 10:37:10PM +0400, Hans Reiser wrote: > > >>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..... >> >> > >So by default with no user space modifications, reiser4 will be atomic for >each write() call, and ext3 will if it aligns withing a single page. > >Is that correct? > Yes.
> >Then you can go on to specify that you can have larger transactions if you >make some changes to the userspace apps. > > > > or you are a programmer who writes code....;-) It's not that hard to write code....;-)
-- Hans
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