Gilles Schipper wrote:
>
> Quite often the error message "STORE ENCOUNTERD A POWERFAIL ON LDEV
> 7" has nothing to do with problems on the indicated tape drive LDEV
> 7.  Rather, they indicate problems with the disk drives that are the
> source of the STORE operation.

Or in more general terms, a SCSI timeout or exception encountered by
LLIO and not passed back up the stack.  I have seen this when it was
legitimately tape (device error recovery exceeded HLIO timeouts) and
non-tape (reset of a SCSI bus).  The "powerfail" is an assumption
that an unresponsive unit has lost power and is probably rooted in
our powerfail recovery heritage in "older" systems as the symptoms
are the same.  You lose power on a non-UPS but battery-backup memory
system and the tape loses its position/tension/whatever and goes
offline, and in that case it is the proper response/diagnosis.  But with
current systems without battery backup memory/UPS-based recovery
this is no longer the case.  The I/O subsystems have not evolved to the
new environment to handle the corner cases (although the error is
retroactive).

Jeff Kell <[log in to unmask]>