krowitz@EDDIE.MIT.EDU@mit-kermit.UUCP (03/11/87)
I was just looking through a flyer annoucing disk drive upgrades
for DN3xx, DN5xx, and DN3000 nodes. The technicals specs lists
the new 190Mb for the DN560/570/580 as having a transfer rate of
only .625 Mb/sec -- slower than the .806 Mb/sec transfer rate of
the 70Mb drive on the DN300/320/330 and *much* slower than the
10.0 Mb/sec rate of the DN3000 disks. Is this a misprint? Why would
the high-end workstations have the slowest disk drives and the
low-end workstations have the fastest disks?
-- David Krowitz
mit-erl!mit-kermit!krowitz@eddie.mit.edu
mit-erl!mit-kermit!krowitz@mit-eddie.arpa
david@mit-mc.arpa
(in order of decreasing preference)mishkin%UUCP@apollo.UUCP.UUCP (03/23/87)
I was just looking through a flyer annoucing disk drive upgrades
for DN3xx, DN5xx, and DN3000 nodes. The technicals specs lists the
new 190Mb for the DN560/570/580 as having a transfer rate of only
.625 Mb/sec -- slower than the .806 Mb/sec transfer rate of the 70Mb
drive on the DN300/320/330 and *much* slower than the 10.0 Mb/sec
rate of the DN3000 disks. Is this a misprint? Why would the high-end
workstations have the slowest disk drives and the low-end workstations
have the fastest disks?
I believe the following summarizes the actual situation. Also, I think
somewhere along the line you may have confused bits/sec and bytes/sec.
Anyway, I am told that as far as the read time goes, the average read
turns out to be faster on the newer machines. Only in sequential tranfers
does the transfer rate advantage of the DN300 family drive have any effect.
Here's the data:
33/70MB SMD 86MB ST412/506 190MB ST412/506 170/380MB ESDI
DN300 X
DN3000 X X
DN5x0 X X
DN5x0-T (Turbo) X X
Interface Transfer rate Capacities Average Seek time
ST412/506 .625 MB/sec 86MB 190MB 28 milliseconds
ESDI 1.25 MB/sec 170MB 380MB 28 milliseconds
SMD (DN300 drive) .8 MB/sec 33MB 70MB 42 milliseconds
(Thanks go to Joe Wadleigh for getting me this data.)
-- Nat Mishkin
Apollo Compute Inc.
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