Re: Is there a performance advantage of adding a second parity set?

Rob, try here inthe Hardware InfoCenter for a place to start cabling

http://publib.boulder.ibm.com/infocenter/powersys/v3r1m5/topic/ipham/scsidiskdriveenclosurei5.htm

Also search on 5787 in the Hardware InfoCenter to see more


On Tue, Feb 16, 2010 at 7:01 AM, <rob@xxxxxxxxx> wrote:

Looking at that...
What I currently have is 3 cables coming off the card. One goes to the
single on top left, one to the dual on bottom right and one to the single
on bottom right. Top right is empty.

I have an extra single. I tried putting in the repeater into top right
and running a cable from the bottom left dual. That doesn't work.

I am hearing that one shouldn't cross from bottom to top with short cable
to go from one repeater to another.

On another frame I have a 5787 and apparently it doesn't matter if the
dual is on the left, or the right because on it the top left is a dual
connected to the single on the top right and the bottom right is a dual
connected to the single on the bottom left.

So, to start out simple with my existing configuration, can I disconnect
one cable from the card and instead of running that to the single on the
bottom right, instead run the jumper from the dual on the bottom right to
the single on the bottom left? If I do this will there be any negative
ramifications, like the one attempt? Can I try it and see if it's
reversable if it doesn't work?
Because, if this works, then the next step would be to take the cable that
came from the card to the single on the bottom right and, instead, run it
to the single on the top right.
Final goal would be:
Cable on card going to dual in bottom left to single in bottom right.
Cable on card going to single in top left.
Cable on card going to single in top right.

Rob Berendt
--
Group Dekko Services, LLC
Dept 01.073
Dock 108
6928N 400E
Kendallville, IN 46755
http://www.dekko.com





From: DrFranken <midrange@xxxxxxxxxxxx>
To: midrange-l@xxxxxxxxxxxx
Date: 02/15/2010 07:47 PM
Subject: Re: Is there a performance advantage of adding a second
parity set?
Sent by: midrange-l-bounces@xxxxxxxxxxxx



Rob,

You are correct, Enabler, Repeater, same gizmo. Two versions
available: one with dual bus (allows pass through to a second repeater)
and has two ports (FC #5742) and one with one bus - one port (FC #5741).

Not having disk units the can shouldn't make it mad at all. Not sure
what's up with that. There are rules as to which slots can have a FC
#5742 and which a FC #5741. If you got that wrong then that could easily
cause the problem. Also you can cable from FC #5742 through to a FC
#5741 but you cannot cable one FC #5742 to a second FC #5742. Part of
the trick with the FC #5742 is it elevates the SCSI addresses of all the
disks in the second Can so that they don't conflict with the first. It
sounds to me like you have an address conflict which would certainly
make some disks 'disappear'. Can't hurt to format and initialize on the
other machine but I don't think it will help.

I believe the rules are on the card in the system but if not the
rules are here:


http://publib.boulder.ibm.com/infocenter/powersys/v3r1m5/index.jsp?topic=/iphal_p5/scsidiskdriveenclosureconfigure.htm


- DrFranken

It was there, the cable from it to the dual was disconnected due to some
issues we are having. I figured out what you call an enabler is what
others might call a repeater.

I think the error I was getting was due to the fact that I had the
repeater there, but no disk drives in the can. I added some disk drives
to the can and got heck. It said the rest of the disks in there are now
missing. So I disconnected the cable again and ripped out the drives.
Hoping it was because they were used by us in another machine. So I am
running them through "format and initialize" on another machine and will
try again.


Rob Berendt

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