[conspire] (forw) Re: June 25 MP installfest upgrade RH 7.3 PC to Centos56 continuation

[Rick Moen]

----- Forwarded message from Rick Moen <rick at linuxmafia.com> -----

Date: Fri, 8 Jul 2011 17:55:54 -0700
From: Rick Moen <rick at linuxmafia.com>
To: wood eddie <ewood111 at yahoo.com>
Subject: Re: June 25 MP installfest upgrade RH 7.3 PC to Centos56
	continuation
Organization: If you lived here, you'd be $HOME already.

Quoting wood eddie (ewood111 at yahoo.com):

I had to think for a minute, to imagine why you would end up with both
narrow-SCSI and wide-SCSI devices.  Then, I remembered that you wrote:

> Had to use SCSI CDROM as terminator for now.

Wow, a SCSI CD-ROM drive.  That's... how can I put this?  Let me try to
put it this way.  On the one hand, you already own it, and it presumably
works, so I can understand your wanting to use it.  On the other hand,
SCSI-type optical drives were never very practical, and you might be
best advised to just retire it and replace it with a dirt-cheap
PATA-type or USB-type CD/DVD drive or even a CD/DVD burner.  

Why?  First, they're so cheap you really lose little, and they'll be far
more useful, far faster, and have long service lives ahead of them.  And
also, you'll no longer need to take special measures to accomodate a
_single_ narrow-SCSI device in addition to your two wide-SCSI hard
drives and one wide-SCSI Adaptec controller.  Which is a bit of hassle 
that goes away if everything on the SCSI chain is wide-type.

Or, err... I just realised, your Adaptec controller _isn't_ wide-SCSI,
is it?  Oh, err....

I may owe you an apology about advising you to get an Adaptec AHA-2940.
I really meant 'Whatever's the appropriate card in the 2940 family, that
best suits what you need to run on it.' It's been so long since I bought
one, I forgot that a _literal_ model AHA-2940 card is strictly a
narrow-SCSI (8-bit bus) card.  I really wasn't stopping to think about
whether you had narrow or wide SCSI hard drives -- but perhaps can be
forgiven because your gear wasn't in front of me.

Adaptec's 2940 family includes later models like AHA-2940UW, where the 'U'
suffix stands for 'Ultra-SCSI', a marketing term for 20 megatransfers
per second, and 'W' stands for wide, or 2-bytes wide per transfer, and
therefore 2 x 20 = 40 megabytes per second capacity for data on the SCSI
bus.  An AHA-2940UW has both a 50-pin narrow-SCSI connector and a 68-pin 
wide-SCSI one.  


----- End forwarded message -----