mounted machine down => df hangs

[Per Hedeland]

In article <2832 at brazos.Rice.edu>, greg at sj.ate.slb.com (Greg Wageman) writes:
>This isn't a bug, it's a feature.
[lots of explanation deleted...]

Well, I'm sure most of us by now have a rather fixed opinion on the truth
of that statement, and I don't really intend to comment on it. However,
something occurred to me while discussing our latest manifestation of that
"feature" (mailtool hanging an entire SunView session because the "mail
server" had become inaccessible:-() - sorry if this has already been
discussed, if so I must have missed it:

As I see it, the purpose of hard mounts is to let programs that don't
handle errors on read/write/etc gracefully (which may in some cases be
hard to do), work "correctly" all the same. On the other hand, most of the
*problems* caused by hard mounts (such as these two examples) seem to be
at *initial* file access, i.e. open/stat/etc. (Or, put another way: Most
programs don't have files open for long periods of time.) Also, most
programs already handle errors at that point - e.g. they are prepared for
an expected file to be missing/ inaccessible etc.

Now, I know next to nothing about how the NFS protocol works, and thus how
feasible this would be, but my conclusion from the above is that it would
be *very* useful to have a soft_open_stat_etc_but_hard_read_write_etc
option when mounting NFS file systems. Anyone got any comments on this?
(Besides "Oh no, not *another* option!":-).

Regards
--Per Hedeland
per at erix.ericsson.se  or
per%erix.ericsson.se at uunet.uu.net  or
...uunet!erix.ericsson.se!per