6.3. Moving a swap file system from a single path device to a multipath device

Procedure

1. Create the /etc/multipath.conf configuration file:

   # mpathconf --enable

2. Enable the multipathd service:

   # systemctl enable multipathd.service

3. If the find_multipaths configuration parameter is not set to on, edit the blacklist and blacklist_exceptions sections of the /etc/multipath.conf file, as described in Preventing devices from multipathing.

4. Add the WWID of the device to the /etc/multipath/wwids file:

   # multipath -a /dev/sdb
   wwid '3600d02300069c9ce09d41c4ac9c53200' added

   Replace /dev/sdb with the swap device name.

5. Confirm that your configuration file is set up correctly:

   # multipath -d 3600d02300069c9ce09d41c4ac9c53200
   : mpatha (3600d02300069c9ce09d41c4ac9c53200) undef 3PARdata,VV
   size=446M features='1 queue_if_no_path' hwhandler='1 alua' wp=undef
   `-+- policy='service-time 0' prio=50 status=undef
     `- 5:0:0:0 sdb 8:16 undef ready running

   Replace 3600d02300069c9ce09d41c4ac9c53200 with the WWID of your swap device.

6. Set up an alias for the swap device in the /etc/multipath.conf file:

   multipaths {
       multipath {
           wwid WWID_of_swap_device
           alias swapdev
       }
   }

7. Edit the /etc/fstab file and replace the old device path to the root device with the multipath device.

   For example, if you had the following entry in the /etc/fstab file:

   /dev/sdb2 swap                    swap    defaults        0 0

   Change the entry to the following:

   /dev/mapper/swapdev swap          swap    defaults        0 0

8. Rebuild the initramfs file system with multipath:

   # dracut --force --add multipath

9. Shut the machine down.
10. Boot the machine.
11. Make the other paths visible to the machine.