Xref: utzoo comp.unix.wizards:6963 comp.sys.dec:573
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From: mangler@cit-vax.Caltech.Edu (Don Speck)
Newsgroups: comp.unix.wizards,comp.sys.dec
Subject: Re: bug report etiquette
Message-ID: <5719@cit-vax.Caltech.Edu>
Date: 10 Mar 88 08:22:37 GMT
References: <2323@umd5.umd.edu> <10102@ulysses.homer.nj.att.com> <3261@bloom-beacon.MIT.EDU>
Organization: California Institute of Technology
Lines: 19
Summary: block device gives no feedback on write errors

In article <3261@bloom-beacon.MIT.EDU>, nessus@athena.mit.edu (Doug Alan) writes:
>			      If the block device is used with the TK50
> drive, the tape drive does stream, and is much much happier.

Somebody here made a similar observation about TU80's, so he did all
his dumps to the block device.	Sometime later he needed to do a restore,
and all his tapes gave a premature EOF.  Dump had been calculating tape
capacity based on 10240 byte blocks, but the block device was writing
2048 byte blocks and it wouldn't all fit.  The tape driver returned
error, but because block-device writes are asynchronous, the completion
status doesn't get returned to anybody, so he had no indication that
writes were not getting done (except perhaps the long pause at end of
tape).

The block device is for mounting filesystems.  Read only.  Which you'd
probably only want to do if your tape drive is actually a WORM.  Didn't
work correctly in 4.2bsd, though.

Don Speck   speck@vlsi.caltech.edu  {amdahl,ames!elroy}!cit-vax!speck