I setup GFS 6.0.0-15 on two IBM xSeries 345 servers running RedHat AS 3.0
server. The plan is to add a third server in the near
future.
Each server has two
QLogic 2312 HBAs (A and B) and are connected to two IBM SAN switches (A and
B). The A HBA on each server is connected to the A SAN switch and the B
HBA on each server is connected to the B SAN switch. The switches are not
connected to each other.
Through the SAN
switches the servers connect to a IBM FAStT600 (non-turbo) storage server.
The A controller on the FAStT600 connects to the A SAN switch and the B
controller on the FAStT600 connects to the B SAN switch.
There are three LUNs
on the FAStT600. LUNs 0 and 2 prefer the A controller on the FAStT600 and
LUN 1 prefers the B controller on the FAStT600.
I have loaded the
QLogic 7.01.01 failover driver for the HBAs on each server.
Everything works
great normally, but if one of the HBAs loses it's connection to the SAN (I
unplug the fiber connection for testing), I start seeing ping-ponging between
the A and B controllers on the FAStT600. The ping-ponging kills
performance of the storage server.
For example, if I
unplug the fiber connection on the B HBA on one of the servers, one server is
still accessing LUN 1 through the preferred path on the B HBA and the B
controller on the FAStT600, but the server where the fiber was removed from the
B HBA is now accessing this LUN through its A HBA and the A controller on the
FAStT600.
When the FAStT600
sees I/O for LUN 1 from one of the servers on its A controller it starts
using the A controller for LUN 1. Then, when the FAStT600 sees I/O for
LUNA 1 from the other server on its B controller it starts using the B
controller for LUN 1. This results in the
ping-ponging.
I have been told
that RDAC will solve this problem, but this isn't currently an option for my
configuration because I do not have the turbo version of the
FAStT600.
Before I spend the
considerable amount of money IBM wants for the turbo upgrade I would like to
know if anyone has gotten failover to work properly in a similar configuration
to what I have using a IBM FAStT600 without the turbo
option.
Thank you in advance
for your help.
--Vincent
