Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!rice!sun-spots-request
From: rocket!dove@uunet.uu.net (Webster Dove)
Newsgroups: comp.sys.sun
Subject: HP ESDI drives can't do continuous xfers?
Keywords: Hardware
Message-ID: <5960@brazos.Rice.edu>
Date: 21 Mar 90 03:19:45 GMT
Sender: root@rice.edu
Organization: Sun-Spots
Lines: 36
Approved: Sun-Spots@rice.edu
X-Sun-Spots-Digest: Volume 9, Issue 89, message 10

We have two drive types on our Xylogics 713 ESDI disk controller (a
7053 workalike).

Mar 19 21:52:08 peach vmunix: xd1: <CDC Wren VI 94196-766 cyl 1630 alt 2 hd 15 sec 52>
Mar 19 21:52:08 peach vmunix: xd2: <HP 97548 793 R2 cyl 1455 alt 2 hd 16 sec 56>

peach# time dd </dev/rxd1c >/dev/null bs=1000k count=10
10+0 records in
10+0 records out
0.0u 0.8s 0:08 10% 0+472k 0+1io 0pf+0w
peach# time dd </dev/rxd1g >/dev/null bs=1000k count=10
10+0 records in
10+0 records out
0.0u 1.1s 0:08 14% 0+472k 1+1io 0pf+0w
peach# time dd </dev/rxd2c >/dev/null bs=1000k count=10
10+0 records in
10+0 records out
0.0u 1.0s 0:15 6% 0+456k 1+1io 0pf+0w
peach# time dd </dev/rxd2g >/dev/null bs=1000k count=10
10+0 records in
10+0 records out
0.0u 1.1s 0:15 7% 0+464k 0+1io 0pf+0w
peach# 

The HP seems incapable of tranferring data continuously.  I have heard
that this is because the head switch time on cylinder of 2ms is too long.
Can anyone share any insight on this?

Dr. Webster Dove				Dr. Webster Dove
Experimental Computing Systems ('X')		Lockheed Sanders Inc.  
Signal Processing Center of Technology		144 Daniel Webster Hwy.
Lockheed Sanders Inc.				Merrimack, NH.  03054  

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