[Nut-upsdev] Suspend-to-disk & NUT

[Charles Lepple]

On 1/7/06, Arjen de Korte <nut+devel at de-korte.org> wrote:
> I have found that it is impossible to communicate with my UPS when
> resuming from a suspend-to-disk state. The driver is no longer able to
> poll the UPS status and eventually will output "Data stale" and never
> resumes. This may have to do with the UPS itself, the driver (SafeNet,
> which I wrote and maintain) or with NUT. Suspend itself is OK provided I
> stop NUT before entering sleep state and start it again after resuming.
> Has someone else experienced similar behaviour?

You may be breaking new ground here - I would guess that most people
who are using suspend-to-disk are using laptops, and would find the
UPS monitoring redundant. (However, I have heard of why this is useful
for servers.)

I haven't used suspend-to-disk much myself, but I think you might be
able to get some useful information from the driver if you tell strace
to attach to it before suspending. (Options such as '-t' can help you
correlate the logs to pre- and post-suspend time.)

Also, is this the kernel suspend-to-disk system, swsusp2, or something
else? It might depend on how the processes are put to sleep. The
kernel version would also be useful.

--
- Charles Lepple