Linux Server

Convert Linux PowerPath Servers to MPIO

 

This document outlines the procedure for switching a SAN boot Linux server running RHEL 5.1 and above from EMC PowerPath to MPIO.

 

Copy the correct /etc/multipath.conf file to the server

 

            (lab1)# cp   /nfs/packages/ga/mpio/RH5/multipath.conf.trpdefault

      /etc/multipath.conf

 

Boot into single user mode

 

            (lab1)# init S

 

Remove the swap device

 

            (lab1)# swapoff /dev/emcpowera3

 

Edit the /etc/rc.sysint script and remove the following section, so PowerPath does not start

 

            ###BEGINPP

      # Configure and initialize PowerPath.

      if [ -f /etc/init.d/PowerPath ]; then

      /etc/init.d/PowerPath start

      fi

      ###ENDPP

 

Replace the lvm.conf file for PowerPath with the default

 

            (lab1)# mv /etc/lvm/lvm.conf.default /etc/lvm/lvm.conf

 

Edit the fstab file, and comment out the line for swap

 

            #/dev/emcpowera3  swap                    swap    defaults              0 0

 

Reboot the server

     

      (lab1)# init 6

 

When the server comes up, remove the PowerPath package

 

            (lab1)# rpm –qa|grep EMC

      (lab1)# rpm –erase EMCpower.LINUX-5.1.x.x.x.x

 

Boot from the rescue disk

 

Skip the load network devices and find installations.

 

At the prompt, run the following commands

 

            (rhel.sh)# mkdir /mnt/sysimage

      (rhel.sh)# mkdir /mnt/sysimage/boot

      (rhel.sh)# multipath –F

      (rhel.sh)# multipath –v0

      (rhel.sh)# mulitipath –l

 

You should see multipath devices now

 

Run the kpartx command to create the device tree entries

 

      (rhel.sh)# kpartx –a /dev/mapper/mapth0

 

Activate the volume groups

 

            (rhel.sh)#  lvm vgscan –config ‘devices{ filter = [   “a/mapper/”,”r/.*/” ] }’

      (rhel.sh)# lvm vgchange –ay –config ‘devices{ filter = [    “a/mapper/”,”r/.*/” ] }’

 

Mount the devices

     

      (rhel.sh)# mount –t ext3 /dev/mapper/rootvg-lv00 /mnt/sysimage

   (rhel.sh)# mount –t ext3 /dev/mapper/mpath0p1 /mnt/sysimage/boot

   (rhel.sh)# mount –t proc none /mnt/sysimage/proc

   (rhel.sh)# mount /dev /mnt/sysimage/dev

   (rhel.sh)# mount /sys /mnt/sysimage/sys

 

Switch to the root directory

 

      (rhel.sh)# chroot /mnt/sysimage

 

Create dm table entries

 

            (rhel.sh)# dmsetup mknodes mpath0

            (rhel.sh)# dmsetup mknodes mpath0p1

            (rhel.sh)# dmsetup mknodes mpath0p2

            (rhel.sh)# dmsetup mknodes mpath0p3

 

 

Edit the file /etc/sysconfig/mkinitrd/multipath and change the line to “MULTIPATH=yes”

 

Remount the /boot directory

 

            (rhel.sh)# umount /boot

      (rhel.sh)# mount /dev/mapper/mpath0p1 /boot

 

Change the /boot/grub/device.map entry to point to the mpath boot device

 

            # this device map was generated by anaconda

      (hd0)     /dev/mapper/mpath0

 

Edit the fstab file to point to the mpath devices

 

            /dev/rootvg/lv00        /                       ext3    defaults        1 1

            /dev/mapper/mpath0p1 /boot                   ext3    defaults        1 2

            tmpfs                   /dev/shm                tmpfs   defaults        0 0

            devpts                  /dev/pts                devpts  gid=5,mode=620  0 0

            sysfs                   /sys                    sysfs   defaults        0 0

            proc                    /proc                   proc    defaults        0 0

            /dev/mapper/mpath0p3 swap                    swap    defaults        0 0

            #

            /dev/mapper/uservg-lv01           /export/home    ext3      defaults 1 2

            /dev/mapper/uservg-lv02           /export/appl/pkgs          ext3      defaults 1 2

 

Create a new ramdisk

 

            (rhel.sh)# mkinitrd –f /boot/HP-initrd-2.6.18-53.1.6.el5.img 2.6.18-53.1.6.el5

 

Create the grub entry

 

            (rhel.sh)# grub-install /dev/mapper/mpath0

 

Disconnect the rescue disk

 

Reboot the server