This week I had the task of working out the details on adding 2 different types of storage arrays to a single host. The host was running EMC’s Powerpath MPIO drivers and Linux LVM. Because powerpath is for EMC devices only I had to remove, convert to multipath to use both storage arrays, and RETAIN the LUN Data. It was pretty easy to remove powerpath, install multiipath but there was an order.
Dismount all the LUNS.
Deactivate any volume groups (vgchange -a n ‘volume group’) .
Install multipath, create working /etc/multipath.conf file, start multipathd.
Filter mpath devices in /etc/lvm/lvm.comf
(filter = [ “a/mapper/.*$/”, “a|/dev/sda[0-9]|”, “a|/dev/sdb[0-9]|”)
Re-activate the volume groups (vgchange -a y).
Update /etc/fstab. (if defined as /dev/mapper/’device’ instead of /dev/’volume group’/’logical volume’ )
The process was fairly simple. I prefer multipath over the proprietary drivers anyway.
With the host now converted to multipath the 2nd storage array could be presented on the host without issue.