Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!uunet!zds-ux!gerry
From: gerry@zds-ux.UUCP (Gerry Gleason)
Newsgroups: comp.unix.i386
Subject: Re: Archive Tapes
Message-ID: <296@zds-ux.UUCP>
Date: 2 May 90 19:02:37 GMT
References: <29490@cup.portal.com>
Reply-To: gerry@zds-ux.UUCP (Gerry Gleason)
Organization: Zenith Data Systems
Lines: 24

In article <29490@cup.portal.com> Dante_A_Nicolello@cup.portal.com writes:
>I am having two problems with an Archive 60 meg Fastape.

>        Tape does not stream. It runs for about 3 seconds, stops.
>Then the HD reads more data, then the tapes rewinds a little and
>goes another 3 seconds and this repeats. This makes backing up take
>a long time. I have tried both tar and cpio. I noticed that if I
>make the buffer size in cpio 51200, it seems to write more data at
>a time. The question is, can it read from the disk and write to
>the tape concurrently? Or is this just wishfull thinking.
>By the way, I have an Irwin 20 meg tape for dos that will read from
>the disk and write to the tape concurrently. The tape streams all the
>way through. 

I'm not even a little surprized.  It is very difficult to get most
tapes to stream, and I'd bet the only reason your Irwin does is that
it is slow.  It is possible with a good SCSI driver that has a good
amount of kernel buffering for the tape (>100k), or some kind of
support for asyncronous I/O in the driver.  With kernel buffering
normal archiving programs like cpio and tar are workable for single
volume backups, otherwise you will need something that know about
the hooks in your driver.

Gerry Gleason