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From: jt34@prism.gatech.EDU (THOMPSON,JOHN C)
Newsgroups: comp.periphs.scsi
Subject: Re: Adaptec SCSI 2 Support
Message-ID: <31579@hydra.gatech.EDU>
Date: 19 Jun 91 13:02:22 GMT
References: <31354@hydra.gatech.EDU> <283400146@adaptx1>
Organization: Georgia Institute of Technology
Lines: 29

In your message you state that the 1740 HBA supports tagged commands in enhanced
mode. Do the 1740 UNIX drivers support this enhanced mode currently? Is this
the 1540 ASW software you mention? Specifically what version of the drivers
offer this support ver ###? Under UNIX is their a programmers interface to send
scsi commands directly to a device - is this the software you wrote which is
often mentioned on the net? How does one obtain these programs - does it come
with the HBA?

We are in the process of developing a scsi based disk array. The actual drives
need only be scsi 1 but the array controller which sits between the drives
and the HBA is scsi 2. This array controller supports both fast mode (10MB/sec)
and tagged commands. The tagged command support is especially important since
in a multiuser environment you would like to have as many of the individual
drives working simultaneously on seperate requests so as to maximize overall
system throughput. As you can tell from my questions a big stumbling block
has been finding the HBA/device driver combinations to support this effort.
My experience thus far has shown that most manufacturers are just beginning
to address scsi 2 issues (and rightfully so). Even the disk array
manufacturers in existence today are only just beginning to understand the
implications of scsi 2 tagged commands and how it affects array performance.
Do SUN, DEC, HP, etc. support tagged commands yet on their workstations?
If anyone has experience with disk arrays either user or developers I would
welcome any input you might have. Please post or email me direct. Thanks.

-- 
THOMPSON,JOHN C
Georgia Institute of Technology, Atlanta Georgia, 30332
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