HP-UX and XP512 question

[Dave Johnson_1]

This is probably a storage question. I have been under the impression that when allocating LUNs from my XP512, I can only assign numbers in the range 0-7F. I just noticed using the GUI for LUN management on the XP, that I can create LUNs in the range 0-FF. Is there a limitation on HP-UX 11.11 and/or 11.23 that I can only go up to 7F or was that a limit to 11.00 (which was the version installed on the servers when the XP hit the DC), or was I miss informed all those years ago and I could have picked the higher numbers all along? If I can, will I see device files with names like c12T18d0 or will they translate to some other c number?

Thanks in advance,
-Dave

[Michael Leu]

Im no expert, maybe this limit could come from the LUN addressing method used by the XP512 for HP-UX hosts:
http://h20000.www2.hp.com/bc/docs/support/SupportManual/c02019264/c02019264.pdf#page=13
(See pages 13-15)

[Dave Johnson_1]

Thanks Micheal.
From reading that document, the part I am interested in is the Target. It looks like that has a range of 0-15 on HP-UX. It is a bit odd then that the XP allows targets 0-127. Anyone know how HP-UX would handle it if I were to assign such a value when assigning space to a server?

[Zinky]

cXtYdZ

Z - lun: (0 to 7)

Y - target (0 to 15)
for every 8 luns, target is incremented

X - controller (bus)
for every 16 targets, X is incremented


So LUN0 from your XP/Hitachi or any array to an 11.0, 11.11, 11.23 HP-UX would be cXt0d0.

LUN9 = cXt1d0
LUN100 = cXt6d4

so forth.

[Michael Leu · Accepted solution]

I just tested this real quick with a old 11.11 box and a HDS AMS array:

LUN Device H/W Path
22 c17t2d6 1/4/0/0.103.0.90.0.2.6
122 c17t15d2 1/4/0/0.103.0.90.0.15.2
128 c29t0d0 1/4/0/0.103.0.90.1.0.0
250 c29t15d2 1/4/0/0.103.0.90.1.15.2

On a 11.31 box with LUNs from the same array:
# scsimgr get_attr -a lunid -C lunpath -I 261
current =0x401c000000000000 (LUN # 28, Flat Space Addressing)
So I think the section with Flat Space Adressing applies.

Maybe the recommendation to only go up to 7F (127) might just be so you don't get a additional cXX device, so that one path to the XP always has only one cXX.

[Dave Johnson_1]

Micheal,
Thanks so much for testing this for me. I really appreciate it.
-Dave

[Dave Johnson_1]

I got confirmation from an HP XP engineer. Michael is correct. TID numbers 16-31 create a new controller number, so I will have to look for that when I allocate in this range.
Thanks again,
-Dave