[Linux-cluster] GFS Multi-pathing and trespassed LUNs

[JACOB_LIBERMAN at Dell.com]

This is a question regarding GFS native multipathing support:

I have a typical redundant mesh topology -- 2 switches, 2 HBAs per host,
2 storage processors. I create the pool device per the procedure
outlined in RedHat KB 4343 and then mount it locally. This works fine.
However, if I trespass the LUN between SPs during a write operation, I
lose all access to it. I have tried pool_mp with both failover and round
robin policies.

Here are my questions:
1. Is there any way to accommodate trespassed LUNs via pool_mp?  
2. Do you need to do anything special (ie remount the LUN, run
partprobe, etc.) to accommodate a trespassed LUN?
3. are the pool_mp policies primarily designed to accommodate front-end
failures? (IE cables, HBAs, switch ports.)

I am using qlogic 2340 HBAs, Brocade switches, and a Clariion CX400
array running R16.

Many thanks, Jacob