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From: krowitz%richter@UMIX.CC.UMICH.EDU (David Krowitz)
Newsgroups: comp.sys.apollo
Subject: Re:  DN570t disks in 10.1
Message-ID: <9003082046.AA03567@richter.mit.edu>
Date: 8 Mar 90 20:46:25 GMT
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A lot of the earlier DN550 and DN560 nodes have ST501 disk
controllers which are considerably slower than the EDSI controllers
used in the DN3000 and DN4000. I believe Apollo switched to
an EDSI controller for the DN570/580/590 with the 348 MB disks,
but if you have the smaller disks the controller may be the same
ST501 controller which is in our DN560. Not only is it slower than
the DN3000, but the cartridge tape uses the same controller -- and
I'm not talking about a multi-function controller that has both a
tape and a disk controller, I'm talking about the *same* controller.
When the tape is reading or writing a block, the disk can not be
accessed and vice-versa. If you try reading a file while the tape
is going, you'll find that there will be a flurry of disk I/O (with
that nice washing machine sound) followed by the tape moving, but
not both at the same time.


 -- David Krowitz

krowitz@richter.mit.edu   (18.83.0.109)
krowitz%richter.mit.edu@eddie.mit.edu
krowitz%richter.mit.edu@mitvma.bitnet
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