> Thanks, Steve, it becomes much clear to me now as why it is. This
> problem is critical to us as we run structure simulation for up
> to several weeks and dump intermediate data every couple hours
> and append them to few large files. If for some reason the system
> crash during data output (though rarely), all the results from
> few weeks running will gone which is unacceptable for us.
> Probably I should looking for FS journaling both meta-data and
> file-data, although I don't really need file-data journaling if
> ever I could get my old content back.
The scenario Steve described obviously does not apply to appending to big
files, because there is no rename() from a temporary file involved.
If it has been flushed they will be on disk. You can force flushing
by using a fsync() for example.