Migrer de Multipath à Powerpath sur RedHat
Contents
1 Introduction
Powerpath is the multipathing solution for EMC arrays. The multipath package is so bugged on RedHat that you shouldn't install it in production environnement. This migration has been released on RedHat 4.6.EL.
Reminder : Multipathing bring redudancy functionnalities with 2 links on a disks array without having I/O errors.
2 Uninstalling multipath
Multipath package name (if installed) can be found by that way :
 rpm
|
rpm -qa | grep multipath |
Next, you just need to bring back the package name and add it to the rpm command :
| rpm
|
rpm -e device-mapper-multipath-0.4.5-27.el4_6.3 |
Now reboot !
3 Installation
Now we'll install the package. Take if from the CD or anywhere else and install it :
| rpm
|
rpm -ivh EMCpower.Linux*.rpm |
Now you'll need to launch the license key command :
| emcpreg
|
emcpreg -install |
Now update the initial ramdisk :
| mkinitrd
|
mkinitrd -f /boot/initrd-`uname -r`.img `uname -r` |
Then reboot again !
4 Powerpath verification
You may need to start Powerpath service :
|
|
/etc/init.d/PowerPath start |
And also may reboot the server again.
Now enter powermt command to verifiy if your LUN can be shown :
| powermt
|
$ powermt display dev=all Pseudo name=emcpowerb ? All the paths below are handled through this pseudo-device CLARiiON ID=APM00023500472 Logical device ID=600601F0310A00006F80C3D32D69D711? Unique ID of LUN (LUN Properties) state=alive; policy=CLAROpt; priority=0; queued-IOs=0? properties/status of the paths ============================================================================== ---------------- Host --------------- - Stor - -- I/O Path - -- Stats --- ### HW Path I/O Paths Interf. Mode State Q-IOs Errors ============================================================================== 2 QLogic Fibre Channel 2300 sdc SP A1 active alive 0 0 2 QLogic Fibre Channel 2300 sde SP B0 active alive 0 0 3 QLogic Fibre Channel 2300 sdg SP B1 active alive 0 0 3 QLogic Fibre Channel 2300 sdi SP A0 active alive 0 0 |
You can also check that you have emc devices :
| ls
|
$ ls /dev/emcpower* emcpower emcpowera |
5 Configuring LVM
Now all is ok, but you need to recover your previous partitions from LVM. So edit the LVM config file, edit it and add thoses arguments :
 /etc/lvm/lvm.conf
|
... filter = [ "r/sd*/", "a/.*/", "a|/dev/sdb[1-9]|", "a|/dev/mapper/.*$|", "r|.*|" ] ... |
Now you can reboot or rebuild the LVM cache :
| vgscan
|
vgscan -v lvmdiskscan |
Now you should see all your disks :-). Look also the /dev/mapper you'll see them too.
