On Fri, 21 Aug 1998, Eduardo E. Horvath wrote:

> 
> I *know* I should never have gotten involved in this.

Ah, welcome to the tarbaby zone....


> > > are plugged in where on a system of any size is a nightmare, since you
> > > never know what physical slot your controller number 1 is plugged into.
> > > Or is it an on-board device?
> > 
> > Thats why I want device ID's which are unique. On a disk it can be the
> > label or a serial-number if you can read it. This would make the same
> > device appear always as the same ID (very handy with removable medias too).
> 
> You do not want to track device by serial number.  One of the purposes of
> this is to be able to replace a broken device by an identical one that
> works.  If you use serial numbers then the new disk I plugged in to
> replace the old one that failed, that has exaclty the same information on
> it as the old one, has a different device ID and device node.  My fstab is
> now useless.

No, no, no, no. Serial numbers are unique. You replace a disk, you
get a new serial number. If you don't get a unique serial number for
two distinct objects, you make reality a surjective mapping. Not
possible except in the movies.

> The other thing to keep in mind with reading configuration files on boot
> is that if the config file is trashed you're pretty much dead.  If that
> happens with Solaris you need to reinstall the OS from scratch because
> even single user mode doesn't work and you need to be an expert on the
> boot process to create the machine maintained files that were lost.

Yes. Ick. That's why a some systems (e.g., AIX, RSX-11) have options to
save the current working image (bosboot, sav /wb resp.) and also
to have an emergency rollback for disaster recovery (mksysb and
dsc11, resp.)

-matt