If you have installed your system on a single-path device and later add another path to the root file system, you will need to move your root file system to a multipathed device. This section documents the procedure for moving from a single-path to a multipathed device.
After ensuring that you have installed the
device-mapper-multipath package, perform the following procedure:
Execute the following command to create the
/etc/multipath.conf configuration file, load the multipath module, and set
chkconfig for the
In order for multipath to build a multipath device on top of the root device as soon as it is discovered, enter the following command. This command also ensures that
find_multipaths will allow the device, even if it only has one path.
multipath -a root_devname
For example, if the root device is
/dev/sdb, enter the following command.
multipath -a /dev/sdb
wwid '3600d02300069c9ce09d41c4ac9c53200' added
To confirm that your configuration file is set up correctly, you can enter the
multipath command and search the output for a line of the following format. This indicates that the command failed to create the multipath device.
date wwid: ignoring map
For example, if the WWID if the device is 3600d02300069c9ce09d41c4ac9c53200, you would see a line in the output such as the following:
Oct 21 09:37:19 | 3600d02300069c9ce09d41c4ac9c53200: ignoring map
To rebuild the
initramfs file system with
multipath, execute the
dracut command with the following options:
dracut --force -H --add multipath
Shut the machine down.
Configure the FC switch so that other paths are visible to the machine.
Boot the machine.
Check whether the root file system ('/') is on the multipathed device.