More than 256 LUNS per HBA Port on direct attached XP1024

[Jim Carter_1]

Is it possible (and if so how) to present more than 256 LUNS per port on the HBA card for a direct attached XP1024? In other words, how do I present 600 LUNS on a single CHIP like CL1A: ? I'd like to use AutoPath to present all LUNS across all connections to the server for load balancing but that requires me to present more than 256 LUNS down a single connection (like CL1A: or CL2A:)

[kris rombauts]

Hi Jim,

i don't know much about the XP but just FYI, be aware their are some limitations from the Autopath side which you might need to take into account also.

You did not specified the OS you are using but this is taken from the readme of AutoPAth V2.01 for Windows 2000 :

VIII. Limitations/Known Problems
---------------------------------

1. The maximum number of unique LUNs supported per server is 252.

2. The maximum number of paths supported per LUN is 8.

3. The maximum number of Host Bus Adapters supported per server is 8.


Also watch your driver spec's for max number of LUNs as well.

Kris

[Peter Mattei]

A single XP1024 port can present up to 512 LUNs. Depending on the Host mode it can be less:
HP-UX = 512
W2k = 256

As Kris wrote this also depends on OS, HBA and multipathing SW max. support.

Cheers
Peter

[Jim Carter_1]

Research results:

The issue with 256 LUNS is based on an XP limitation, so it really doesn't matter which O/S you are using as long as it can support at least that number. The only way you can present more than 256 LUNS out a single port on the XP HBA (like CL1A:) is to use SecureLun and two host groups. BUT, you can not assign a single WWNN to more than one host group, so we are back at our original limit of 256 when we are direct connected.

You could FAN-IN if you were SAN attached but you could also create a huge bottleneck and performance problem.