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From: egisin@june.cs.washington.edu@watmath.UUCP (Eric Gisin)
Newsgroups: mod.computers.vax
Subject: error recovery on MUA:
Message-ID: <8612152138.AA24746@watmath.uucp>
Date: Tue, 16-Dec-86 08:42:49 EST
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Posted: Tue Dec 16 08:42:49 1986
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I spent a day copying some save sets on TK50 tape to save sets on disk.
I normally use `mount mua: volume /block=8192' then just copy them. 
There was a parity error in the third save set,
and this caused the ACP to get confused when it came to that error
(even if I was trying to access the fourth save set).
I managed to copy the fourth save set by mounting /foreign,
and I copied the third with something like:
$ backup MUA: [...]
$ backup [...] saveset/saveset
where backup reported a recoverable error when reading the tape.

My questions are:
- why can't the ACP recover from a data error,
and
- what does backup do to recover from errors that
copy, the ACP or RMS, or the device driver don't do?