5.3. Moving root File Systems from a Single Path Device to a Multipath Device
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.confconfiguration file, load the multipath module, and setchkconfigfor themultipathdtoon:#
mpathconf --enableFor further information on using thempathconfcommand to set up multipathing, see 第 3.1 节 “Setting Up DM Multipath”. - If the
find_multipathsconfiguration parameter is not set toyes, edit theblacklistandblacklist_exceptionssections of the/etc/multipath.conffile, as described in 第 4.2 节 “配置文件黑名单”. - 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_multipathswill allow the device, even if it only has one path.#
multipath -a root_devnameFor example, if the root device is/dev/sdb, enter the following command.#
multipath -a /dev/sdbwwid '3600d02300069c9ce09d41c4ac9c53200' added - To confirm that your configuration file is set up correctly, you can enter the
multipathcommand 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:#
multipathOct 21 09:37:19 | 3600d02300069c9ce09d41c4ac9c53200: ignoring map - To rebuild the
initramfsfile system withmultipath, execute thedracutcommand 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.
