Re: soft updates and qmail (RE: qmail IO problems)

[Alfred Perlstein]

* Andre Oppermann <[EMAIL PROTECTED]> [010206 12:30] wrote:
> Rik van Riel wrote:
> > 
> > On Tue, 6 Feb 2001, Andre Oppermann wrote:
> > 
> > > But please answer me one question: Is the link() call atomically
> > > in FFS/UFS w or w/o softupdates? Meaning when the call returns
> > > the meta- data is written to stable storage like with fsync()?
> > 
> > Since when does `atomic' equal `synchronous' ?
> 
> Because otherwise it would not be atomically, would it?

Softupdates does it atomically but not synchronously. :)

Basically, the in-memory view of the filesystem != the on-disk
version.

The update happens atomically with respect to locking in memory,
so running processes never see a non-atomic snapshot of the directory,
but if a crash occurs the disk may be several steps behind the
memory at the time of the crash.

-- 
-Alfred Perlstein - [[EMAIL PROTECTED]|[EMAIL PROTECTED]]
"I have the heart of a child; I keep it in a jar on my desk."


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