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Date:	Sat, 30 Aug 2003 03:25:44 PDT7
From:	"Info 4 SYNass" <Info@SYNass.NET >
Reply-To:	scoug-help@scoug.com
To:	scoug-help@scoug.com
Subject:	SCOUG-Help: What SCSI adapter to choose !?

Content Type: text/plain

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Hi Steve
Starting from the end of your very interesting reply:

Why "Sorry for the length of this post ..." ???

Your answer meets all my expectations pefectly ;-)
It includes all answers to my questions ;-))
Even more: It also names some brands and types of HA ;-)))

Your answer is so exact and precise to me to make my decision !!!

I will try to answer into your text below:

scarter@vcnet.com on 30.08.2003 08.47.35
Please respond to scoug-help@scoug.com
To: scoug-help@scoug.com
cc: =

Subject: SCOUG-Help: What SCSI adapter to choose !?

>Svobi: =

>
>Dual channel SCSI host adapters make a LOT of sense for backwards =

>compatibility reasons. Although SCSI is both backwards and (somewhat) =

>forward compatible, the HA will operate the bus at the lowest common =

>denominator (speed) of whatever is on the bus.

I was assuming or thinking like the above ;-)

>So, ... =

>using a dual bus host adapter, you can separate the old, slow, SCSI
devices, =

>i.e. ZIP, MO, CD-ROM, and scanner from the newer faster, hard drives.
ALL =

>LVD (low voltage differential) adapters will revert to single-ended if
even =

>one device on a bus is single-ended, so a dual U160 HA can run one of
its =

>buses as SE for our older legacy devices. External devices, e.g.
scanners, =

>often have long cables which further compounds the speed problem with
SE SCSI. =

>External cables, with their multiple connector interfaces, do not
preserve =

>the bus impedance very well and SCSI bus data fidelity can suffer at
the =

>higher bus speeds of FAST and Ultra SCSI (SE). =

> =

>For me, and many others, the best solution is a dual bus HA,
separating =

>the old, slow and external legacy (SE) devices from my (more) modern =

>Ultra 160 10Krpm (LVD) hard drive(s). The best physical design
(inside/outside =

>the computer box) keeps the cable run as short as possible, and uses =

>active termination at the end of the cable. Using one bus dedicated to =

>legacy SE SCSI may limit the number of SE devices to 7, depending on =

>configuration. Most external devices, except hard drives, are SE.

However I do not use faster units at the moment, =

my intention is / was to keep the option for any future changes ;-)

>Dual U160 HAs generally have two internal 68-pin LVD/SE connectors, =

>as do _EVERY_ONE_ of the HAs listed below, and a varying complement of =

>other connectors. Here are some HA choices I have been investigating.
=

>There are others, but not of interest to me: =

> =

>LSI Logic (dual channel, 30 devices max): =

> LSI 21040; one 50-pin internal header for legacy devices, 1x 68p
external
> 64-bit PCI
> LSI 21003; one 50-pin internal header for legacy devices, 1x 50p
external
> (this HA is hard to find) 32-bit PCI =

> LSI 22915A; two VHDCI external connectors, 64-bit PCI
> =

>Adaptec (dual bus, but not dual channel -- 15 devices max.): =

> AHA 29160; one SE bus and one U160 bus, but 15 devices total max., =

> 1x 68-pin U160 external. 64-bit PCI
> AHA 29160N; one 50-pin bus (internal and external) and one internal
U160 =

> limited to 15 devices total, but _GREAT_ for legacy
support.
> ($129 at scsi4me.com) 32-bit PCI =

> AHA 39160; 2x 68-pin VHDCI external, 1x 50-pin SE, 64-bit PCI
> =

>Tekram (uses LSI Logic SCSI chips, dual channel, 30 devices max): =

> DC-390U3D: 2x U160 LVD channels; 2x 68-pin VHDCI external, =

> 1x 50-pin internal; 64-bit PCI =

> DC-390U3D: 1x U160 and 1x SE channel; 1x 68-pin external LVD, 1x
68-pin =

> internal SE, 1x 50-pin internal SE; 64-bit PCI
>
>The retail Tekram packages come with a lot of cables and
connector/adapters, =

>making them a good deal. Tekram.de announced a U320 SCSI HA, but it
has =

>not yet appeared anywhere that I've seen -- status unknown.

=46rom your mentioned types I would keep along the Adaptec or the LSi
types.
Another source has suggested the (hard to find) LSi 21003 ;-))
Since I am reconsidering I never discovered one ;-(

>If your motherboard doesn't have 64-bit PCI slots, you can still =

>use a 64-bit PCI card provided you have clearance for the additional =

>connector length. My AT MB is _SO_ old that this a problem and even =

>longer PCI cards don't fit. Modern ATX MBs should not be much =

>of a problem, but it's worthwhile to check first.

My mobo isn't quite old but how do I recognize or differ a 32-bit PCI =

to a 64-bit one ??

>U320 dual HAs are also a good choice, but typically have _NO_
50-pin/SE =

>legacy connector support. Not a problem if you're willing to use an
adapter =

>and sort out the wide-to-narrow transitions in cabling and
termination. =

>SCSI4ME.com is a good place to start shopping. eBay also has some
good =

>prices, especially on the U160 LSI22915A for which you must use a =

>68-to-50 pin adapter and have room for an 8.5" long card. =

> =

>Adaptec has a history of NOT providing drivers for their older HAs =

>and newer operating systems. There are no Window XP drivers from some =

>of the older Adaptec HAs, so they are readily available on the surplus =

>market for cheap. This is good news for OS/2 users who want an
inexpensive =

>SCSI HA for their older devices. The OS/2 drivers haven't changed =

>and are available. =

>
>Still, my money will probably go to LSI Logic. They are the former
NCR =

>Microelectronics folks and their HAs show up in SUN, HP, Compaq
machines =

>and even have Linux drivers. There are OS/2 drivers at the u160 level
too. =

>For U320, you probably have to go a recent (merged, v4.52) kernal to
get/use =

>U320 drivers. Steven had a post recently about this. Upon reflection, =

>he's likely right.

U320 is not a topic today and U160 may become a topic with changing my
system =

from OS/2 Warp 4 FP16 to Warp 4 MCP 2 with the recent 4.52 kernel !?

With your interesting explantation and naming the specific units =

I am able to study a and reconsider my specific needs ;-) =

I will have a better eye now for looking and searching on eBay ;-))

> --Steve (sorry for the length of this post... )
Once again, Steve, thanks a lot for your efforts and this very helpful =

and interesting assistance and hints ;-)))

Have a nice weekend
svobi

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