Fix for 8 lun limit

[Paul Wewel]

I heard there is a patch out to extend the 8 lun limit in 11.0. Anyone know about it?

[Marcel Eken_2]

Hi Paul,

There is not a patch for ux 11.x to increase the numbers of lun's. I think that if you can't get more then 8 lun's it is probably a limitation of the devices attached to the scsibus.

For example an autoraid 12 or a Nike FC/30 supports only 8 lun's.

Marcel,

[Patrick Wessel]

Marcel,
It's a limitation from the OS, not from the array. There are only 7 Bit for the value of the LUN.

Paul,
I'm not aware that there is a patch to change that Limitation.

[Stefan Stechemesser]

SCSI-2 only uses 3 bits for adressing the LUN - that's the reason why only 8 LUNs can be accessed. SCSI-3 will theoretically allow 2^64 LUNS, but currently HPUX 11.0 still can only handle 8 LUNS ...

[Patrick Wessel]

my fault, of cause it's just 3 bit...

[Paul Wewel]

I heard there was something called "volume set addressing", that was originally only enabled for certain devices that HP supported. It basically only used 8 LUN's but enumerated the path number for each additional 8 LUN's. I heard it was generally released for all devices in 11.11. I was looking for some details on how you take advantage of this.

[Andy Monks]

There is an enhancement request to increase the limit, currently being considered by the lab. I don't know the status however.

[Patrick Wessel · Accepted solution]

For more information about VSA check the "FC60 Advanced User's Guide" page 217-220
You find the manual at this location: http://www.hp.com/essd/download/fc60_adv.pdf

[Paul Wewel]

Great info. Thanks. So is VSA in 11.11 open to anybody or is it still restricted to HP "approved disks" meaning they sell it disk arrays?

[Dave Wherry]

Paul,
Are you thinking of Fibre Channel? There you can have multiple targets on the same controller:
c2t4d0 - c2t4d7 &
c2t5d0 - c2t5d0 and so on. I think the limit is 128 LUNs on a channel.

[Paul Wewel]

Yes, fibre channel arrays. Most of them will support up to 32 lun's under a target but in order for the HP-UX systems to have access to all these volumes they must implement the volume set addressing method to get above 8 per target. This is described well in the FC60 document referenced earlier in this thread but what I have been told is you have to be one of HP's array types in order for them to allow this extended addressing. I also heard that in 11i they may have made this open to all disk arrays. How would one obtain HP-UX 11.11 (11i) upgrade? Is it out on the web or do I need to order it through HP? Does anyone know if this is open now and whether there is a spec available that describes how you need to present yourself in Inquiry and Report Lun's commands to take advantage of it?

[Dave Wherry]

Paul,
I've actually not heard of volume set addressing. I may be using it and not realize it.
I've used EMC Symmetrix, HP XP256 arrays and FC30 arrays. They would all be considered one of HP's array types. On both UX 10.20 and 11.0 on these array types I have not had more than 8 LUNs per target. However, I have had multiple targets per card giving me many more than 8 LUNs on the EMC and XP. With the performance of the FC30 I do not want that many LUNs. I want to get off of it.
I inherited the 10.20 systems and as is typical they were Highly Patched (HP). The 11.0 systems I built and added the XP256 to them. As with any HP product there was a list of patches to install. I can't tell you if any of them specifically addressed the set addressing method. One or more might have.
As for 11.i, I saw in the HP World magazine that it will be released this fall. No date set.
When you ask "how you need to present yourself in Inquiry and Report Lun's commands", again I can't tell you anything specific. The inq command for EMC and the xpinfo command for the XP256 have always worked with reporting these LUNs. Nothing special to do.