Migrate from StorageTek D280 to EMC-CX4 Clariion with RHEL 4U4 RDAC Kernel

Hi all,

I was wondering if anyone's had the opportunity to migrate a RHEL 4 server running a modified Linux kernel that includes Engenio's RDAC in the initrd image from a StorageTek SAN to EMC PowerPath on Clariion?

PowerLink only has one pertinent post that is for a Windows server running Veritas VXVM + DMP + RDAC, and I have some concerns as I can't Google anything on a proven working migration process (which tells me no one's really done this and documented it). Looking for confirmation of any of the following scenarios:

1. Reboot into vanilla, non-RDACized kernel, update Qlogic drivers (QLA2340) install EMC PowerPath, use "inq" utility to locate identical LUNs on STK, add EMC disk to the LVM2 volume group, use pvmove to migrate data from STK to EMC LUN device, remove old STK from volume group.

2. Leave RDAC modified kernel on system, try installing EMC PowerPath , add EMC disk to volume group, pvmove data from STK to Clariion, remove old STK from volume group.

For option 2, I hope to soon have a test system (that is currently a production system going through a data migration to another server) available that I could try these options upon. However, I have concerns as I hear PowerPath and RDAC do not get along (same holds true for PP and Linux MPIO).

Questions I have:

If I go with option 1, and boot into a vanilla kernel, sans RDAC, I "believe" I would see multiple paths (whence the need to identify which disks are identical with EMC's "inq" utility. Does anyone have any thoughts on this?

If I go with option 2, and leave the modified RDAC kernel alone (having PowerPath and RDAC on the same server at once), does anyone portend data corruption / hung server / end of the world and general doominess?

There's also option 3, which I probably have to consider as well:

3. Based on EMC's Grab utility's recommendation, upgrade the Qlogic driver, install new kernel, make new initrd, install RDAC (or not), and generally enter into new unknown territory on an unknown kernel (the kernel could be solidly proven to someone else, but not yet in my shop).

But option 3 is really simply a rehash of options 1 & 2 and understanding what to expect during the migration. Any advice is appreciated.

System details:

[root@prltec01 ~]# lsmod | grep ql
qla2300 129792 0
qla2xxx 307576 1 qla2300
qla2xxx_conf 305924 1
scsi_mod 116941 10 mppVhba,qla2xxx,libata,mptsas,mptspi,mptfc,mptscsi,mppUpper,sg,sd_mod

[root@prltec01 ~]# lsmod | grep mpp
mppVhba 103424 13
mppUpper 84512 1 mppVhba
scsi_mod 116941 10 mppVhba,qla2xxx,libata,mptsas,mptspi,mptfc,mptscsi,mppUpper,sg,sd_mod

[root@prltec01 ~]# cat /etc/modprobe.conf
alias eth0 tg3
alias eth1 tg3
alias scsi_hostadapter mptbase
alias scsi_hostadapter1 mptscsih
alias scsi_hostadapter2 ata_piix
alias scsi_hostadapter3 qla2xxx_conf
alias scsi_hostadapter4 qla2300
alias usb-controller ehci-hcd
alias usb-controller1 uhci-hcd
options scsi_mod max_scsi_luns=255 scsi_allow_ghost_devices=1

install qla2xxx /sbin/modprobe qla2xxx_conf; /sbin/modprobe --ignore-install qla2xxx
remove qla2xxx /sbin/modprobe -r --first-time --ignore-remove qla2xxx && { /sbin/modprobe -r --ignore-remove qla2xxx_conf; }
### BEGIN MPP Driver Comments ###
# Additional config info can be found in /opt/mpp/modprobe.conf.mppappend.
# The Above config info is needed if you want to make mkinitrd manually.
# Please read the Readme file that came with MPP driver for building RamDisk manually.
# Edit the '/etc/modprobe.conf' file and run 'mppUpdate' to create Ramdisk dynamically.
### END MPP Driver Comments ###

alias bond0 bonding
options bonding miimon=100 mode=1

############### >>>>>>>>>>> We use mppUdate to create new initrd files <<<<<<<<<<<<<<<###################

[root@prltec01 ~]# cat /etc/r*release
Red Hat Enterprise Linux ES release 4 (Nahant Update 4)

[root@prltec01 ~]# mppUtil -V
Linux MPP Driver Version: 09.01.B2.01

[root@prltec01 ~]# modinfo qla2300
filename: /lib/modules/2.6.9-34.ELsmp/kernel/drivers/scsi/qla2xxx/qla2300.ko
author: QLogic Corporation
description: QLogic ISP23xx FC-SCSI Host Bus Adapter driver
license: GPL
version: 8.01.05 204868D2F9BA2C32F657B45
vermagic: 2.6.9-34.ELsmp SMP 686 REGPARM 4KSTACKS gcc-3.4
depends: qla2xxx
alias: pci:v00001077d00002300sv*sd*bc*sc*i*
alias: pci:v00001077d00002312sv*sd*bc*sc*i*
alias: pci:v00001077d00006312sv*sd*bc*sc*i*

[root@prltec01 ~]# uname -a
Linux prltec01.lawson.com 2.6.9-34.ELsmp #1 SMP Fri Feb 24 16:54:53 EST 2006 i686 i686 i386 GNU/Linux

Cheers,
Andrea