Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!cbmvax!uunet!rbj
From: rbj@uunet.UU.NET (Root Boy Jim)
Newsgroups: comp.unix.wizards
Subject: Re: Finding tape block size
Message-ID: <124231@uunet.UU.NET>
Date: 27 Feb 91 23:36:37 GMT
References: <1991Feb12.224353.6514@gjetor.geac.COM> <15222@smoke.brl.mil>
Organization: UUNET Communications Services, Falls Church, VA
Lines: 18

In article <15222@smoke.brl.mil> gwyn@smoke.brl.mil (Doug Gwyn) writes:
>Assuming your tape subsystem conforms to long-established UNIX practice,
>if the read() system call specifies a read count less than the actual
>block size when reading the "raw tape" device (which is the usual one),
>you should get an I/O error since data will be lost.

I agree with everything Doug said. However, I would like to add that
while mtio(4) says that an error will be returned, many device drivers
will not return one. The only source (Tahoe) I have available to look
at (Lions is at home) says things like:

/*
 * If we were reading raw tape and the only error was that the
 * record was too long, then we don't consider this an error.
 */
-- 
		[rbj@uunet 1] stty sane
		unknown mode: sane