Thanks to all who have responded. We have ordered the correct parts...

Joe

-----Original Message-----
From: HP-3000 Systems Discussion [mailto:[log in to unmask]]On
Behalf Of PAUL,GUY (HP-Boise,ex1)
Sent: Wednesday, October 15, 2003 12:12 PM
To: [log in to unmask]
Subject: Re: [HP3000-L] Fibre Channel switch question


Yosef writes:

>Brocade switches also allow what they call
>QuickLoop which is a hybrid of FC-AL and FC-SW.

Correct, with an additional license cost. Our Brocade
rep actually discourages the use of QL.

>The difference between fabric and FC-AL is that FC-AL is a
>series of addresses connected together. Each is required to
>negotiate for access to the loop. The device with the lowest
>WWN, World Wide Name always wins.

Actually the device with the lowest AL-PA address wins. The FL_port
is always 00 and the highest NL_port can be EF for a total of 126
NL_ports in a loop.

> There are limits to how many devices, i.e. logical units,
> each adapter can handle. The maximum allowed may not give the
> best performance. YMMV.

HP's recommended limit of no more than 15 8gb luns per A6795A is
way too conservative imo. This goes back to the 0-15 (minus SCSI 7)
address limitation. In a SAN environment you should be able to push
500GB per HBA when any part of your SAN is running 1GB/sec up to
1TB/sec per HBA if your entire SAN is 2GB/sec.

If you are also using HAFO/iX divide those numbers by 2 otherwise you
will overload your HBA if a path fails.


>
> The N-Class has 12 adapter slots. The A-Class has 4 adapter
> slots. I am not sure if you can put an A6795A in slot 1 on
> the A-Class.

Native fiber is not supported on the A-class.

Guy Paul



> -----Original Message-----
> From: HP-3000 Systems Discussion
> [mailto:[log in to unmask]] On Behalf Of Yosef Rosenblatt
> Sent: Wednesday, October 15, 2003 6:36 AM
> To: [log in to unmask]
> Subject: Fibre Channel switch question
>
>
> Joe,
> The Fibre Channel Adapter is an A6795A. This is a 2GB adapter
> that uses LC connectors. (LC is the smaller connector. SC is
> the large one.) The cost, last I looked, was was in the $2,100 range.
>
> This adapter will allow you to connect to your disc drives.
> You can do this through a switch, a hub or direct connect.
> Different technologies exist to connect your server to your
> storage. FC-AL, Fibre Channel Arbitrated Loop, is the
> default. If you connect through a direct connection or a hub
> you will have an FC-AL connection. You can also use FC-AL
> through a switch. Brocade switches also allow what they call
> QuickLoop which is a hybrid of FC-AL and FC-SW. FC-SW is
> switch mode or fabric mode.
>
> The difference between fabric and FC-AL is that FC-AL is a
> series of addresses connected together. Each is required to
> negotiate for access to the loop. The device with the lowest
> WWN, World Wide Name always wins. This can cause bottlenecks.
> All Fabric devices have direct access to each other not to a
> loop. They are connected to what is called a cloud. Through
> this amorphous connection all devices send and receive to all
> other devices.
>
> There are limits to how many devices, i.e. logical units,
> each adapter can handle. The maximum allowed may not give the
> best performance. YMMV.
>
> The N-Class has 12 adapter slots. The A-Class has 4 adapter
> slots. I am not sure if you can put an A6795A in slot 1 on
> the A-Class.
>
> Work For Peace
>
> Yosef Rosenblatt
>
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