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FC10 and loop id

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Marta Gomez
Occasional Advisor

FC10 and loop id

Hi all!
I've got an FC10 connected to two machines through a switch brocade. I've put the enclosure id 0 and in one machine I see the hardware paths from 8/ to 8/ and in the other machine I see from 0/4/0/ to 0/4/0/
My question is, is correct that i see the same disks with different loops id in differents machines?
This question comes because i receive multiples messages of the EMS about this hardware like "drive is not responding", "I/O request failed", "driver detected a NOS/OSL storm",...



p.S. This thread has been moved from Disk to Disk Array. - Hp forum moderator

Oliver Haensel
Respected Contributor

Re: FC10 and loop id

Hello Marta,
you're using 2 different addressing methods. I assume the 2 servers are connected to 2 different FC10 Controllers (LCC cards).. Let's decode the ioscan outputs:

8/ through .0.9.0 means you have a K- or D-class server connecting in private loop topology where the disks are directly attached using peripheral device addressing.
The disks have the loop IDs 0 through 9 which corresponds to the slot numbers because the enclosure ID is set to 0.

0/4/0/ through .14.15.0
means you are on a N- or L-class server connected to a Brocade switch (switch domain ID 2) in fabric point-to-point topology. On port 4 of the same switch the FC10 is connected in private loop topology too, peripheral device addressing is used as well (parameter 255).
13.6 is the decimal value for the ALPA 0xD6 which corresponds the the loop ID 9 where 14.15 is ALPA 0xEF (loop ID 0).

So you see the same disks at different loops (if connected to 2 different LCC cards) but with the same loop IDs because these loop IDs are fix due to enclosure ID and disk slot where the disk resides. All what differs is the addressing scheme.

So 8/0.8...0.0.0 is the same disk as 0/4/0/0...14.15.0!!!

Hope this helps

everything is possible ...