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Q: SCSI terminology ... need external hard drive ... ( Answered 5 out of 5 stars,   1 Comment )
Subject: SCSI terminology ... need external hard drive ...
Category: Computers > Hardware
Asked by: subu62-ga
List Price: $5.00
Posted: 15 Nov 2002 11:23 PST
Expires: 15 Dec 2002 11:23 PST
Question ID: 108451
I am confused with all the terminology used in SCSI. Specifically, I
would like to know about the various Ultra-SCSI terms. Ultra2, Ultra160,
Ultra320, LVD ..
and the various connectors. 68-pin, 50-pin, high-density, SCA .. etc. etc.

All this because ...

I am trying to find an external hard drive for a HP B180L workstation.
This machine has an Ultra Wide SCSI 68-pin high density connector. Which SCSI
drives would work ? If I get an LVD drive am I OK ? Am looking for a
drive around 36 GB. It currently has a Seagate ST3457WS 4GB drive internally.
I don't want to fiddle around inside the box to replace this drive. Instead,
I want to get an external drive.
Subject: Re: SCSI terminology ... need external hard drive ...
Answered By: haversian-ga on 15 Nov 2002 20:59 PST
Rated:5 out of 5 stars
Hello subu62,

Ultra2, Ultra160, and Ultra320 are (reasonably vague) terms referring
to the signalling standard used.  LVD stands for Low Voltage
Differential (in contrast with HVD, High... which is not used much
anymore).  LVD is a scheme for lowering power consumption, but more
importantly increasing resistance to signal degradation due to
external fields.

There are several 68-pin SCSI connectors, several 50-pin connections,
an 80-pin SCA (single Connector Attachment) standard that routes both
power and data through the same cable.

Storage Review, a well-respected hard drive review and information
site, has an extensive guide to all things storage.  Part of their
reference collection deals with SCSI and can be found at
 It will answer all your questions, and more, though it may be

The SCSI standards are backwards-compatible, so if you go get yourself
a blazing fast U160/m hard drive, you can plug it into an older Ultra2
(also known as SE, single-ended, since it requires different
termination) controller.  There are even converters from SCA to
68-pin, from 68-pin to 50-pin, etc.  If your components are reasonably
new, you pretty much just plug them in and everything works.  Older
SCSI devices, like older IDE devices, are more particular about what
they work well with.

If you are going to plug in an external drive, you will need the
appropriate cable (VHDCI, typically.  Very High Density Connector
Interface) to an external enclosure which will provide power and
termination for the drive.  You can purchase such enclosures from any
number of places (request a clarification if you need one) and put
your own hard drive (or two, or three, or... they come in a variety of
sizes) into it.

If you need help with this specific situation, rather than general
SCSI information, ask for a clarification and I'll see what I can come
up with.  Otherwise, best of luck with the maze of SCSI standards. 
While complicated in theory, SCSI is really fairly simple in practice.

Have fun!


Request for Answer Clarification by subu62-ga on 16 Nov 2002 06:02 PST
Hello Haversian-ga:
   Thank you. As one of the other commenters suggested, firewire
drives are bigger and cheaper. However ..
  I am NOT using a PC. I am using HP 180L workstation running HP-UX
It does NOT have a firewire interface. HP-UX, I don't think support
IEEE1394 yet.

I am looking for an EXTERNAL (I think the SCA to ... adapters are
small internal cards, right ? ) drive around 36 GB that will directly
connect to my EXTERNAL
Ultra-Wide SE port.

Most of the ones I found on the net, are LVD with SCA connectors.
The other ones I found are in the thousands of dollar ranges for a 18

$2000 for a 18GB drive ? I might as well buy a PC and run Samba to
just mount
a bigger drive for that money, right ?

Clarification of Answer by haversian-ga on 16 Nov 2002 14:12 PST
It's true - SCSI carries a price premium, but for $2000 you can buy
Seagate's huge old 180G drive - 36G should cost around $200.

Do you have an external enclosure already?  If not, that will cost
about $100-500 depending on how big / fancy it is.  I can probably
find one for you if you'd like.

Pricewatch lists quite a few 36G SCSI drives, some with SCA
connectors, some with 68-pin connectors.  The page you probably want
is at ( ), which lists
drives in the $160 range.  The external SCSI connector you have is
probably a VHDCI connector, but when you buy an external enclosure, it
will come with that connector externally, and have a SCSI backplane
inside where you can plug your drive in.

Is this what you're looking for?

Request for Answer Clarification by subu62-ga on 17 Nov 2002 08:53 PST
Thank you, haversian. 

I don't have an external enclosure. I would like an external --
drive with power supply etc --. The search on pricewatch for external
came up with only 2 results costing around $400.

(search on: scsi 36.7 external)

Do these come with a cable or do I have to buy separately ?
I don't want to buy something and again spend a lot of time trying to
a cable that connects the drive to my machine.

I just need something I can connect these to my HP B180L machine that
says Ultra Wide SCSI SE ?  (68 pin high density). I don't know if this
is what you
are referring to as VHDCI ? Don't think so, though.

Is there some place that has pictures of all these various connectors

Thanks again for all your help.

Clarification of Answer by haversian-ga on 18 Nov 2002 03:34 PST
You don't really get external drives with self-contained PSU and such
- you get a regular internal drive and a case that it comes in.  The
external Firewire drives you may have seen are done that way - it's a
regular IDE drive inside.  Same with external CD burners and such.

I'm not absolutely positive what connector you have.  It sounds like
what I'm calling VHDCI connectors, but if you could point to what
connector it is on this page (Storage Review:
) I'll know for sure.  Converters (and converting cables) are
available for pretty much any conceivable combination of SCSI
connectors, though it's always nice when things match without that

For an enclosure, you can go with a multidrive unit that you can
expand later, or there are some pretty small single-drive units
available.  You sound like you only want the one drive, so here are
some options:

Single-drive chassis, 68-pin high-density connector:

The same company, Micro Accessories, makes a selection of enclosures -
the main page is here:

If you have a free 5.25" drive bay, you might consider a removable
hard drive in lieu of an external one.  Enclosures such as these ( ) are available from a number of
suppliers.  One advantage of the removable bay is that you probably
already have a SCSI cable in your case, which would save you about $50
versus the external option.

In either event, you will probably want an SCA drive, which will just
slip into whatever case you purchase for it.  Conveniently enough, SCA
drives are cheaper than others, as there is less demand.  If you are
willing to go with a used drive, you can save even more.

Do you want me to pick a cable / enclosure / drive combination for you
or would you rather choose them yourself?

Request for Answer Clarification by subu62-ga on 18 Nov 2002 07:25 PST
I have the HD 68pin connector. I think the site refers to this as Alternative 3.

Your idea of getting an enclosure sounds very good for future expansion.
Could you find me a nice combination of cable/enclosure/drive ?

Thank you for all your help.

Clarification of Answer by haversian-ga on 19 Nov 2002 03:46 PST
Sure.  How big (number of bays) would you like the enclosure to be? 
Do you want one that will also accept 5,25" devices such as CD-ROM
drives?  Do you need brackets to mount a 3.5" drive in a 5.25" bay, or
do you have some already?  How important are size and speed and price?
 That is, do you have a target size, idea of how fast it needs to be
(10K rpm or 15K rpm?), or a target price, either for the drive or the
whole kit?

Request for Answer Clarification by subu62-ga on 19 Nov 2002 11:46 PST
Maximum 4 bays. 5.25" would be nice. Can I then put a DVD-ROM in it ?
Does the DVD-ROM need to be SCSI also ?

No, I don't have any brackets to fit a 3.5" drive in a 5.25" bay.

First and foremost though, I just need to have extra disk space available.
I am willing to spend around $400 for the whole kit. Speed doesn't really matter.
The processor I have is not that fast anyway. A 180MHz PA-RISC processor.

This is mainly for experimentation. No serious work !

Thanks again. I really love this service ! What a great idea. Usually I do the
research for people on the net. It's nice, for once, to have someone else help me !

Clarification of Answer by haversian-ga on 19 Nov 2002 17:58 PST
> Maximum 4 bays. 5.25" would be nice.
   Hyper Microsystems ( ) has a good
reputation and offers free shipping if you mention
in your order.  Their prices are not the lowest possible but they are
reasonable and service is good.  They offer a selection of 2- and
4-drive enclosures with the right connectors such as the ESB-34-HD68
(4-drive) and FHC-5021-HD68 (2-drive).  Cables are available in 1, 3,
and 6-foot lengths (MDB68MDB68-1, MDB68MDB68-3, MDB68MDB68-6).

> Can I then put a DVD-ROM in it ?

> Does the DVD-ROM need to be SCSI also ? 
   Yes.  There is a very nice slot-loading Pioneer drive, the 305S
(which I have) that's only about $120 - check Pricewatch.  You will
need an adapter to convert from 68-pin to 50-pin (and this will slow
your hard drive down to the speed of the DVD drive, which I believe is
> ... $400 ...
   The enclosure and cable will run you about $200, leaving $200 for
the hard drive.  Hyper Micro also sells drives for you, such as the

$199   36G 15,000RPM IBM drive
$109   18G 10,000RPM Quantum/Maxtor drive
$219   36G 10,000RPM Quantum/Maxtor drive
$149   18G 10,000RPM Seagate 36ES
$232   36G 10,000RPM Seagate 36ES

The IBM drive will be the fastest, and has the lowest price at that
capacity point, but runs extremely hot and also very loud.  I would
recommend one of the Seagate and Quantum drives - pick whichever you
prefer.  If you are willing to go with a less reputable reseller, you
can find on Pricewatch ( )
drives as large as 73G for just over $200 but service and reliability
will likely suffer.

Enjoy your new SCSI setup!

subu62-ga rated this answer:5 out of 5 stars and gave an additional tip of: $2.00
Great service. The researcher never got tired of my persistent questioning !

Subject: Re: SCSI terminology ... need external hard drive ...
From: funkywizard-ga on 15 Nov 2002 13:45 PST
I don't know a whole lot about scsi, so I would recommend you consider
getting an external firewire hard drive, they are very fast. I realize
you are looking for scsi, so this is simply a suggestion.

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