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Problems with RSCN on fabric (SAN) attached HP-UX box.

Posted on 2007-08-06
Medium Priority
Last Modified: 2013-12-06
uname output.
HP-UX HOSTNAME B.11.11 U 9000/800 108444660 unlimited-user license

I have a Fibre Channel Attached HP box and have an issue when I move targets to different FC ports on my switches.

Whenever I try to change a target device to a different port on my FC switches (Brocade), HP-UX doesn't recognize the change.  It still sees the paths as dead.  All other flavors of UNIX and Windows hosts don't have this issue.  They pick up the changes just fine.  Does HP-UX not process RSCN automatically?  Is there a way I can tell it to manually refresh FC devices and pick up the switched ports?

I am not using PVLINKS, I am using EMC PowerPath and LVM.  I only use soft zoning in my FC environment.

Question by:flood_land

Expert Comment

ID: 19642399
I was not able to rescan disks in HP-UX myself. It required a reboot. However, it did work.

Author Comment

ID: 19645804
If I add LUNs that works fine.

I'm just trying to migrate to a newer switch.  All other hosts seem to work fine, it[s just my HP-UX servers that don't seem to update when I move target devices to different ports.  It doesn't even work if I move to a different port on the same switch, or a different switch connected through ISL.
LVL 21

Expert Comment

ID: 19649105
As I understand it, PowerPath replaces the functionality of LVM alternate links (AKA PVlinks). When adding (or moving) a LUN, you need to run `ioscan -f` to discover new paths, then `insf -e` to create the device files for those paths.  At that point PowerPath should be able to see the "new" LUN and detect that it's a known disk and resume intercepting calls to the old device file.

Until you reboot,  the old paths will be seen as failed in ioscan, but LVM should not detect the change.

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Author Comment

ID: 19653942
I kno wyou can do some neat things with fcsmutil and I was hoping I could use some FC command to sort of rescan my FC enviroment and recognize any changes made.  I was really hoping to be able to change ports without rebooting :(.

The LUNs aren't an issue here really.  I just want PowerPath to recognize when I change FC ports.  Soft Zoning usually does thi sjust fine.  My experience so far is HP-UX is absolutely horrible with being SAN attached.  Most of our hosts are NFS attached for this reason.  it might also be the fact that we are on an older release.
LVL 21

Accepted Solution

tfewster earned 2000 total points
ID: 19657095
I'm not clear if you're saying that ioscan _doesn't_ detect the new paths?

Again, as I read it, RSCN enabled switches and cards will only detect that there has been a change in the SAN. I see nothing to indicate that the operating system should create new device files automagically on that basis.  And it seems reasonable to me that ioscan in HP-UX  should continue to report that a device is missing, whether you use PowerPath or PVLinks to access the new path.

Author Comment

ID: 19670945
With soft switch zoning (zoning based on WWPN, rather than physical port) you should be able to switch ports and RCSN should update the pathing and the path should return to normal.  i.e. I unplug an HBA that is plugged into port 5 on an FC switch, then move it to port 6 PowerPath will reconnect the path and everything should be fine.  It wont' change the scsi information or anything.  Just trying to change the switch port.

This works with any OS other than HP-UX.  The path will show as dead until I move it back to the original FC port that was plugged in.  The purpose of soft zoning is to be able to do this without any problems.

I just want to know if there is a command or something I need to run manually.  Below is just a screen of  what my patchs look like when everything's good.  When I change ports some will come back as dead.

> powermt display
Symmetrix logical device count=0
CLARiiON logical device count=9
----- Host Bus Adapters ---------  ------ I/O Paths -----  ------ Stats ------
### HW Path                        Summary   Total   Dead  IO/Sec Q-IOs Errors
 12 0/8/0/                optimal       8      0       -     0      0
 13 0/8/0/                optimal       8      0       -     0      0
 17 0/12/0/               optimal       8      0       -     0      0
 19 0/12/0/               optimal       8      0       -     0      0
 29 0/12/0/               optimal       1      0       -     0      0
 30 0/12/0/               optimal       1      0       -     0      0
 31 0/8/0/                optimal       1      0       -     0      1
 32 0/8/0/                optimal       1      0       -     0      0

Expert Comment

ID: 20316350
I think what you are wanting is available in HP-UX 11iv3... you are probably using an old version of HP-UX.
LVL 16

Expert Comment

by:Hanno P.S.
ID: 21086507
No comment has been added to this question in more than 21 days, so it is now classified as abandoned.

I will leave the following recommendation for this question in the Cleanup Zone:
Accept tfewster's comment as answer.

Any objections should be posted here in the next 4 days. After that time, the question will be closed.
JustUNIX, Experts Exchange Cleanup Volunteer

Expert Comment

ID: 21130372
Forced accept.

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