LUN configuration

[galenr]

When connecting multiple HP hosts to a single port on a mass storage array, must I have a lun 0 on each hdd at each host and must my luns be numbered contiguously ?

Thanx in advance

[James R. Ferguson]

Hi:

There was a problem at one time that required contiguous LUN assignments without gaps. I believe too, that the first assignment had to be zero.

I believe patches were issued for 10.20 and 11.x releases some time ago, however. If you have recent patches you should be OK.

Regards!

...JRF...

[galenr]

Thanx James ... so... do the patches alleviate the need for the lun 0 as well as the contiguous numbering, or just the latter ?

[Ashwani Kashyap]

I believe LUN0 is still needed . THe patches alleviate the need of contiguouf LUNS only .

[James R. Ferguson · Accepted solution]

Hi:

This was reported and fixed in 10.20, in patch PHKL_22224, which noted "ioscan will not discover devices (LUNs) that follow a non-existent LUN on a given target. Ie. ioscan will only currently find existent LUNs that are in sequential order starting from LUN 0. Therefore, such "non-contiguous" LUNs will not be seen by ioscan and will not be accessible to the system. This behaviour had been seen with a EMC disk array, but may exist with other devices."

I can't find any more information relative to 11.x, however.

Regards!

...JRF...

[James R. Ferguson]

Hi (again):

OK, in 11.0 see patch PHKL_21607. This is clear:

"The stated limitations on lun numbering are that they must start at zero and be in sequential order. If there are any "gaps" in lun numbering, ioscan will not recognize the high order luns above the gap. The request is for ioscan to recognize all luns, regardless of lun numbering and order."

Regards!

...JRF...

[Bill McNAMARA_1]

There was certainly a problem relating to EMC arrays and sequential lun numbering.

This was discussed in the storage forums about a year ago. If you've got 11.00 and no EMC, don't worry - you can even have a non existing lun0 -- although it'll show up on the ioscan whether it exists or not.

This still happens on nike arrays, you have auto-tresspass on, yet you still see the lun 0 throught the two SPs, quite annoying, but again, if we're not talking nikes then there's no problem.
Later,
Bill