Path: utzoo!attcan!uunet!wuarchive!julius.cs.uiuc.edu!rpi!uupsi!camb.com!bruce
From: bruce@camb.com (Barton F. Bruce)
Newsgroups: comp.sys.dec
Subject: Re: 'real' speed of SCSI vs. SDI vs. DSSI
Message-ID: <1991Jan30.000109.39521@camb.com>
Date: 30 Jan 91 05:01:08 GMT
References: <1991Jan25.204122.18983@herald.usask.ca>
Organization: Cambridge Computer Associates, Inc.
Lines: 27

> THE QUESTION IS: am I right in saying that the SCSI interface is a major
> bottleneck making the 3100 a poor choice for a boot node in a small cluster??

There are those nice 11 ms 3rd party SCSI drives, or if you want to
save a tad, you can buy the slow 15 ms ones. Some brands may be a tad
slower but offer 150000 to 200000 hour MTBF WITH a 5 year warantee.
Think of all the money you won't pay field service. 

For what you would have paid DEC, you can buy a pile of them. Do get
some processor you can put tons of cheap memory on, and with enough
extra CPU power (won't take much more) to run something like Executive
Software's IOEXPRESS. 

IOEXPRESS, given a few cpu cycles and lots of memory, will give you
some amazing cache hit percents. The 11 ms disks are very nice, too.
Most real world users hit seek time limits, NOT xfer limits. More
spindles helps here, too. 

If you get a Q bus machine with the right 3rd party controller, you
can hang CDROMS (for DEC's software distribution + online DOC
service), all your disks, and 4 or 8 mm backup tape drives on it. 

Buying an all DEC solution is great if you can afford it. Mix and
match shopping from some OEM that knows what works is often a better
deal. 

Have fun!