topic Re: IO Timeout and Powerpath in Operating System - HP-UX

IO Timeout and Powerpath

Peter Marais — Wed, 02 Nov 2005 07:11:41 GMT

How do I change the IO timeout param with emc powerpath installed. Tried pvchange -t but it comes back with:
pvchange: Physical voulume :/dev/dsk/c4t0d0" could not be changed:
No such device or address.

pvdisplay /dev/dsk/c4t0d0 has no problem in listing the parameters.

Re: IO Timeout and Powerpath

Cheryl Griffin — Wed, 02 Nov 2005 07:25:37 GMT

This will happen if the pvchange process times out.

Check your Powerpath version. You may have to update it.

Re: IO Timeout and Powerpath

Peter Marais — Wed, 02 Nov 2005 07:31:46 GMT

The Powerpath version is HP.4.3.0 I beleave it to be pretty resent. Also the pvchange command fails immediately. No delays

Re: IO Timeout and Powerpath

Cheryl Griffin — Wed, 02 Nov 2005 07:45:50 GMT

Have you made any changes on the EMC and if so have you tried a reboot and the pvchange again? If changes are made, the disk driver may no longer be communicating so the disk looks like it's not there.

If this does not help, someone in the Response Center can help you if you open a call.

They need to analyze an lssf, ioscan, a pvdisplay, diskinfo -v, look at the drivers in the kernel (specifically scsi drivers) and if there are any associated messages in syslog. There are some internal tools they can provide you that can help analyze the situation as well.

Re: IO Timeout and Powerpath

Peter Marais — Wed, 02 Nov 2005 08:02:49 GMT

What I would like to know is weather anyone tried to change the io timeout paramater while powerpath is installed. I have just been recommended to change the value from default to 90 seconds (by emc grab). The system is behaving normally and I do not want to spend time on this.

Re: IO Timeout and Powerpath

Florian Heigl (new acc) — Wed, 02 Nov 2005 10:09:49 GMT

can You supply the full command and output, and also a lssf /dev/dsk/c4t0d0 and lssf /dev/rdsk/c4t0d0 ?

To answer Your question: I never tried it in a power path config, for we only use pvlink on our hp-ux boxes. You should clarify with EMC^2 if You really need to set it - in my experience it's crucial in Clariion/CX + pvlink environments and close to irrelevant with PowerPath and i.e. DMX.

OTOH the default of 30 seconds is a bit short for hot-wiring fibre links ;)

Re: IO Timeout and Powerpath

john kingsley — Wed, 02 Nov 2005 13:54:57 GMT

Yes, I was able to change the timeout value on my physical volumes, and I am running powerpath ver. 4.2. EMC reccomended a value of 180 sec. I'm not sure if it maters, but check to see if you are running pvchange on the primary path.

Re: IO Timeout and Powerpath

Peter Marais — Thu, 03 Nov 2005 02:31:36 GMT

Thanks everyone for the interest so far. I am attaching a file of what I did.

Re: IO Timeout and Powerpath

john kingsley — Thu, 03 Nov 2005 08:11:37 GMT

Do you know where the dead path came from?
It can be removed by running:
powermt check dev=path

Re: IO Timeout and Powerpath

OFC_EDM — Thu, 03 Nov 2005 10:17:07 GMT

Regarding the "no such device or address".

We used to have similar issues when adding LUNS.

But now before we do anything with the EMC disks we do the following:

1. powermt check
--> if it prompts to remove dead paths we remove all.

2. If adding LUNS we create them and assign them to the host at this point via Navisphere.

3. ioscan -fnC disk
4. insf -C disk
5. powermt config
6. powermt save
7. Then we review everything with powermt display dev=all and make sure it matches up with Navisphere.

This is only loosley related to your issue in that we do this to ensure dead paths are removed and that the devices you see with pvdisplay really exist.

Cheers.

Re: IO Timeout and Powerpath

Peter Marais — Fri, 04 Nov 2005 04:03:45 GMT

Tried removing the unknown path but could not. See attachment

Re: IO Timeout and Powerpath

OFC_EDM — Fri, 04 Nov 2005 17:03:39 GMT

What's the output from

ioscan -fnC disk

?

Re: IO Timeout and Powerpath

OFC_EDM — Fri, 04 Nov 2005 17:13:54 GMT

Did you have an HBA replaced recently?

Re: IO Timeout and Powerpath

sathish kannan — Fri, 04 Nov 2005 18:56:51 GMT

Hi Peter,
Looks to me you replaced a HBA or changed the instance before removing those devices from Powerpath. Have a look into the "ioscan" output and check for H/W path with no hardware or unknown status and the run "powermt check"

Regards
Sathish

Re: IO Timeout and Powerpath

Peter Marais — Mon, 07 Nov 2005 02:06:37 GMT

We had a path change some time ago where EMC replaced one of there switches for a newer one. This caused the path change and regenned the device files. All the unknown paths and old device files have been removed. Also should the powerpath check command not also remove the unknown device from EMC? How do i repair this the system has been rebooted after cleaning up the device files so a reboot will not cure this. Also the HBA's are functioning fine so no problem there. Rechecked ioscan -fnC and all devices displayed are claimed.

Re: IO Timeout and Powerpath

Bernd Reize — Mon, 07 Nov 2005 08:52:26 GMT

To remove a dead hba form powerpaths config you have to issue "powermt remove hba=6" manually. (Please verify the controller instance number, before doing this!)

Re: IO Timeout and Powerpath

Peter Marais — Mon, 07 Nov 2005 09:30:39 GMT

Tried to remove it, no sucksess.

Re: IO Timeout and Powerpath

Milton Lin_3 — Wed, 09 Nov 2005 14:04:06 GMT

If you still see UNKNOWN paths,

couple of things to try....
1.#powermt check
or
#powermt check force
2. Check from the SAN/Navisphere the connectivity status and verifiy the number of paths/connections.
3. #isocan -fnC disk then #powermt config

------------
Timeouts as I have seen vary depending on Clarrion and Symmetrix. I've seen recommendation of 90 seconds for Powerpath and 180 seconds for PVLINKS
------------
good luck

Re: IO Timeout and Powerpath

Peter Marais — Thu, 10 Nov 2005 01:56:22 GMT

Thanks Lin but I have tried that already.

Re: IO Timeout and Powerpath

sathish kannan — Thu, 10 Nov 2005 22:54:54 GMT

Hi Peter,
You need to rebuild your powerpath database.
Take note of your current configuration and rebuild powerpath configuration.

Regards
Sathish