> > afaik, only disk-specific part of diskstats is its name.
> > yes, you can just seek=0 for tapes.
> > 
> 
> Perhaps at the moment but what if we considered keeping stats for all
> the partitions on a disk individually?  Solaris does this and I think
> it would be a nice idea to implement for us - at the moment you can
> only tell which _disk_ is busy, sometimes it can be very helpful to
> know that /var is being thrashed by something...

well, how about migrating to wedges and make them gather statistics?  :)
i personally hesitate to add more partation handling code.

> > to me, "if (tape)" doesn't seem to be needed, at least for disk_unbusy().
> > 
> 
> True, but it would be for attach (or just have a different attach) due
> to all the extra information associated with a disk attach.

sure.
maybe isolate common members between disk and tape
into a sub structure, so that they can use a common attach routine?

YAMAMOTO Takashi