topic Re: disk hw path changed after fiber channel failure in Operating System - HP-UX

disk hw path changed after fiber channel failure

Sana Chaarani — Mon, 11 Jul 2005 13:30:20 GMT

Hi,

We have several hp-ux servers running 11i
connected to a xp1024 enterprise storage.
The port in the fiber switch where one of our
servers is connected, failed. All disks viewed on this server using this fabric, went no_hw. If I want to change the connection from port 9 to port 8, for example, all hw paths of my disks will change , right ? How can I recover from this ?

Thanks for your help,

Sana

Re: disk hw path changed after fiber channel failure

Devender Khatana — Mon, 11 Jul 2005 13:38:25 GMT

Hi,

You will have to use vgimport command on all the new devices achived after changing the port. This shall recreate the vginformation with the new device files and the path.

Morover if it is a mcdata switch, the port hardly goes bad & there is a SFP module which fits into the port, which generally goes bad. This module can be replaced easily among different ports.

HTH,
Devender

Re: disk hw path changed after fiber channel failure

D Block 2 — Mon, 11 Jul 2005 14:57:20 GMT

are you balancing HBA's on your server ? maybe auto-path ? So you are running for the moment fine ? If you. make certain you also run: vgcfgbackup on your vg's. and copy your /etc/lvmtab before you do any export/imports.

Re: disk hw path changed after fiber channel failure

Pradeep_29 — Mon, 11 Jul 2005 21:06:17 GMT

If you are using Emulex HBAs you can do persistent binding.

If you are using default Taychon cards, I am not sure you can do persistent binding or not.

But, as suggested, you would need to do vgimport if hw paths change. They may not change in all scenarios.

Re: disk hw path changed after fiber channel failure

Stuart Powell — Tue, 12 Jul 2005 06:08:08 GMT

Sana,

Are the zones on the FC switch set up as port to port, or by aliases? I use a Brocade fabric switch and assigned the zones using the WWN addresses for each HBA. In my case I can move a FC connection from one port on the switch to another on the same switch with no change in device defintion.

Though I haven't worked in a port to port switch I would think that if you redefine the zone definition, maintaining the same zone, you shouldn't cause any path changes.

Stuart

Re: disk hw path changed after fiber channel failure

Marek Smejkal — Wed, 13 Jul 2005 02:58:38 GMT

indeed your dev files changed changing the switch port, the best way is just replace SFP from unused port (or spare one) to the original switch port.
Marek

Re: disk hw path changed after fiber channel failure

Stuart Abramson — Wed, 13 Jul 2005 05:08:26 GMT

If you have a High Availability configuration, i.e. - two HBAs connected to two switches connected to two disk ports, (which is the way your should have odne it) then you still have access over the other connection. You just lost one connection. Don't panic!

Don't shutdown and do a vgexport/vgimport. You can fix this on the fly.

Just fix the switch port, reconnect everything (live - while the application is running), do a discovery sequence (ioscan, insf -e) and vgextend the new disks back into the VG. (don't pvcreate them! They already have data on them!)

If you only had one path to the volumes, then you have to do vgexport/vgimport; but you should ALWAYS have two paths.

Re: disk hw path changed after fiber channel failure

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Re: disk hw path changed after fiber channel failure

Torsten. — Thu, 16 Mar 2006 14:53:46 GMT

If you have (port-)zoning configured, every port number is essential.

Otherwise beside the internal HW-path (PCI-slot) and the LUN ID only the switch domain ID and the port on the switch where the storage is connected are important for the HW-path and the device file. The port where the server is connected is not.

So you can swap the port for the server, but not the port for the XP array.