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Non sequenced LUNs

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Vince Inman
Frequent Advisor

Non sequenced LUNs


I would like to know what patch resolved the problem on HP-UX 11 where LUNs presented to the HBA had to be in sequence for the HBA and Host to properly see the devices.

I have experienced this feature a number of times with EMC arrays and have always insisted upon getting devices presented to the host in a sequential manner so as to ensure that all devices were seen by the host.

Thanks

6 REPLIES
A. Clay Stephenson
Acclaimed Contributor

Re: Non sequenced LUNs

I've never seen the behavior you describe either in 10.20,11.0, or 11i. I've created and destroyed LUN's with abandon with with multiple
SCSI controller's on the same bus. The RAID LUN's always appeared as expected.
If it ain't broke, I can fix that.
Patrick Wallek
Honored Contributor
Solution

Re: Non sequenced LUNs

I think patch PHKL_22759 is what you are looking for. Have a look at http://us-support.external.hp.com/cki/bin/doc.pl/sid=08bb2b2e119d58495c/screen=ckiDisplayDocument?docId=200000054213098 for more details. There were a couple of newer patches, but they have been recalled due to other problems.

Note that this patch depends on PHKL_18543, which if it is already installed and you attempt to re-install it, can really cause you problems.
Insu Kim
Honored Contributor

Re: Non sequenced LUNs

That issue is one of the assignment rlues applied to EMC disk array itself.
That is, LUNS should be in the string in order to be visible to the host.

And HP has applied the same rule to XP-array but with a new released microcode, what XP-array does is to trick the host into thinking LUN0 and the string are available by creating a pseudo devices for each SCSI target ID so you can see pseudo device by issuing "ioscan" even if a LUN is not assigned.

Because HP achieved this under the microcode level of the array, it would be better to ask for information about that from EMC support personal.

Regards,

Never say "no" first.
Bill McNAMARA_1
Honored Contributor

Re: Non sequenced LUNs

yes it has,
this was called the LUN gap problem and occured when, on EMCs for example you deleted a LUN 3 for example, LUN4 and greater vanishes

I can't recall exactly the patch, I'll ask around.

Later,
Bill
It works for me (tm)
Ron Lawson_1
Trusted Contributor

Re: Non sequenced LUNs

Yes, PHKL_22759 is the right patch to get for HP-UX 11.00. There was also an earlier patch, PHKL_21607 that also included this fix.

Note that some customers with large numbers of LUNs have experience much longer boot times with PHKL_22759 installed (because we are now spending time scanning the "LUN holes"). We are working on a complementary patch to improve the boot times.

Ron Lawson
project manager, hp-ux mass storage
Ron Lawson_1
Trusted Contributor

Re: Non sequenced LUNs

Two patches are available today. PHKL_24004 is the latest SCSI patch for 11.00, which includes the fix to look for non-sequenced LUNs. PHKL_24187 dramatically reduces boot and ioscan times for large fibrechannel configurations. Enjoy!

Ron Lawson
hp-ux mass storage r&d