Re: Pre-approval request for dpkg sync() changes for squeeze
Guillem Jover wrote:
> 1) Switch back from sync() to fsync() before rename() (while keeping
> the sync() code around for the benefit of other distributions
> that might not want to switch just yet). So to avoid unrelated
> I/O when there's background work being done for example. This
> hack also only works on Linux where sync() is synchronous, so
> it would unify that code path for all dpkg supported platforms.
> Bug: #588339
Will there be a NEWS.Debian.gz entry for this? I fear that the
performance degradation would be unacceptable to some people (using
ext4, for example).
> 2) Add a new --force-unsafe-io to disable those fsync() for people
> using certain file systems where the only option is to choose
> between reliability or acceptable performance.
dpkg uses the "rename trick" in all the cases this applies to, right?
If so, a certain degree of reliability is guaranteed in precisely
those file systems where fsync() is slow.
What risks remain with --force-unsafe-io on those filesystems?
Context: a good part of ext3's popularity comes from its combination
of speed and resiliance to crashing. To sacrifice one of the two is
sacrificing something dear to some people.