Am 04.02.2015 um 15:02 schrieb Rushton Martin:

Our cluster was supplied with two IBM DS3400 RAID arrays connected with fibre channel. Both are old and one is failing so we bought an IBM V3700 to replace it. The V3700 complained that we were using the IBM's RDAC driver (true) and we were advised to change to using Linux multipath. I've done that but the default configuration for the DS3400s

So you switched from IBM's proprietary multipath driver to the native Linux multipathing. Correct?

is: device { vendor IBM product 1726-4xx path_checker rdac features 1 queue_if_no_path hardware_handler 1 rdac prio_callout /sbin/mpath_prio_rdac /dev/%n no_path_retry 300 rr_min_io 1000 }

The right settings are documented here:

https://access.redhat.com/solutions/85223

Yoi should be a little more specific about the conflict you see.

The V3700 is still complaining and I note the "path checker rdac" and mpath_prio_rdac lines. Is this rdac the same as IBM's RDAC, and if so how can I get rid of it?

The DS3400 is an OEM product, provided by NetApp. RDAC is the the name of the hardware access type originally for LSI Corp controllers, later on NetApp.

mpath_prio_rdac is code from the Linux kernel.

OS is CentOS 5.3 (yes, I know - upgrade), filesystem is GPFS.

Update! Not upgrade. That old piece of software is full of well known severe security issues and bugs already fixed. There is not really an excuse to not properly maintain a system.

Alexander