topic Re: Query on Proactive polling in Operating System - HP-UX

Query on Proactive polling

Avinash20 — Fri, 04 Dec 2009 08:25:17 GMT

http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=1147216

With reference to the above thread, could you please provide any docs which talks about proactive polling causing trespassing in Clariion.

Re: Query on Proactive polling

Michal Kapalka (mikap) — Fri, 04 Dec 2009 08:34:17 GMT

hi,

check this on powerlink.emc.com

for example :

https://community.emc.com/message/410196

but if you don't have acoount you need to register.

mikap

Re: Query on Proactive polling

Avinash20 — Wed, 03 Feb 2010 11:37:58 GMT

I will post my answers once I find a perfect explanation.
As per my analysis, this should not be required.

Re: Query on Proactive polling

Avinash20 — Wed, 24 Feb 2010 01:03:49 GMT

When HP initially released the LVM proactive polling, they made sure that hpux recognizes their on active/passive array types and were able to avoid trespass storms there that way.

EMC contacted HP engineering, and
HP came up with the solution that proactive polling can be turned off with pvchange -p n command for being able to avoid excessive trespassing with other than HP active/passive arrays.

HP LVM originally utilized INQUIRY requests for its proactive polling implementation, however several years ago moved to utilizing READ requests to block 0 of the device. This behavior change presented a problem for EMC Clariion active /passive configurations with auto-trespass enabled in that the READ request arrival on the non-owner SP would trigger a trespass for that device, where as INQUIRY requests do not result in a trespass event. This made for a requirement to disable proactive polling for this type of configuration.

To summarize LVM proactive polling has to be turned off in case of PVLINKS setup.

For other type of configuration proactive polling can remain enabled, however if there is an underlying multipathing product such as Powerpath it would serve to handle path fault detection and IO request redirection as well as redirect the proactive polling READ requests to other path(s), so LVM proactive polling would serve no useful purpose in this scenario since LVM is above the multipathing product, but also harmless.

Re: Query on Proactive polling

Avinash20 — Sun, 04 Apr 2010 21:59:34 GMT

Proactive polling should be disabled in case of HP-UX PVlinks

Re: Query on Proactive polling

Avinash20 — Wed, 10 Nov 2010 09:01:03 GMT

Proactive Polling can be disable via
# pvchange -p n /dev/dsk/cXtYdZ