topic disable proactive polling in Operating System - HP-UX

disable proactive polling

Alain BLANC — Thu, 16 Apr 2009 13:21:10 GMT

Hi everyone,
could I try the command pvchange -p n /dev/dsk/c1t0d0s2 when my cluster in on whithout be afraid by any other result than disabled proactive polling from my disk ?
Shortly could I run this command in a warm or need I run it in a cold state ?
Thanks so much

Re: disable proactive polling

Steven E. Protter — Thu, 16 Apr 2009 13:30:14 GMT

Shalom,

You should if you have concerns try your code in a non production lab.

Maybe tell us a little bit about your environment and this disk:

1) MCSG version
2) OS version
3) Is the disk a cluster lock disk
4) Is the disk part of a shared storage array
5) What you mean by use of terms cold state and warm state. I'm not going to assume, I want to know in order to provide you good help.

SEP

Re: disable proactive polling

Avinash20 — Thu, 16 Apr 2009 13:32:21 GMT

"pvchange -p" I dont see that option in man page of pvchange :(

Re: disable proactive polling

Avinash20 — Thu, 16 Apr 2009 13:34:13 GMT

Oops.. I got the infomration about -p option.
Thanks

Re: disable proactive polling

Alain BLANC — Thu, 16 Apr 2009 14:04:57 GMT

thanks Steven
I work with 4 servers, 2 rx3600 in a cluster and 2 other RX3600 in a second cluster.
HP-UX B.11.23, Serviceguard A.11.17.00, OVU 8.53
The concerned disks are in a LUN linked to 2 clusters.

ClusterA ClusterB
NodeA1 NodeA2 NodeB1 NodeB2
\ \ | /
\ \________ | ___/
\_____________ \ /
\_ LUN

When a package failover from NodeA1 to NodeA2, the shared space is dismounted from nodeA1 and mounted to nodeA2.

I hope having answered correctly to your question.
many thanks for your help
Alain

Re: disable proactive polling

skt_skt — Thu, 16 Apr 2009 16:32:03 GMT

what is the reason you want to disable proactive polling? This is on by default. What diff r u expecting after making the change?

Re: disable proactive polling

Torsten. — Thu, 16 Apr 2009 16:37:49 GMT

/dev/dsk/c1t0d0s2 is likely the boot disk.

Why do you want to change this?

Re: disable proactive polling

Bill Hassell — Fri, 17 Apr 2009 02:03:41 GMT

Proactive polling was added in an LVM patch several months ago. Unfortunately, it was turned on automatically for every disk in the system. For internal disks, it's fine as the LVM code periodically polls all the disks to see if they are still alive. The idea is to possibly catch an error condition before real data is affected. So for JBOD (non-array disks like internal) it is fine.

However, for smart disk arrays such as EMC, Hitachi, IBM, Axiom, HP, etc, for path managers such as PowerPath, DynaPath, etc and for specialized SAN appliances such as products from FalconStor, this proactive polling interferes with performance and is a waste of CPU and I/O cycles. In a smart array, all management of disk failures is completely hidden from the host (as it should be).

You can remove proactive polling with pvchange -p n . The pvchange command will not have the -p option if the LVM patch level is quite old. You can do it during production but for volumes with lots of alternate paths, it can take 3-6 seconds per lvol. This is a one time change. Unfortunately, there is no way to change the default setting so adding any new disks (LUNs) will require turning the polling off.

Re: disable proactive polling

Alain BLANC — Fri, 17 Apr 2009 05:46:23 GMT

All my clusters are monted in a CLARiiON CX3-series bay.
The disk admin team are many alarm with tresspasses and open a call to EMC support who answer this :
All your disk have the proactiv polling ON.
Fix Proactive polling should be turned off.
Autoswitchback should be set to no.
CLARiiON is an active/passive array. No probing should be done on the passive side. That will cause trespasses.

Note These settings apply only to volumes presented from the array not the local drives.

Thanks for your help
Alain