5.4. Disabling multipathing by device name

Procedure

1. Display device information:

   # udevadm info --query=all -n /dev/mapper/sd* 

2. Disable devices in the /etc/multipath.conf configuration file by using the devnode entry.

   The following example shows the lines in the DM Multipath configuration file that disable all SCSI devices, because it disables all sd* devices as well:

   blacklist {
          devnode "^sd[a-z]"
   }

   You can use a devnode entry to disable individual devices rather than all devices of a specific type. However, this is not recommended because unless it is statically mapped by udev rules, there is no guarantee that a specific device will have the same name on reboot. For example, a device name could change from /dev/sda to /dev/sdb on reboot.

   By default, DM Multipath disables all devices that are not SCSI, NVMe, or DASD, by using the following devnode entry:

   blacklist {
          devnode "!^(sd[a-z]|dasd[a-z]|nvme[0-9])"
   }

   The devices that this entry disables do not generally support DM Multipath.

3. Validate the /etc/multipath.conf file after modifying the multipath configuration file by running one of the following commands:

   • To display any configuration errors, run:

     # multipath -t > /dev/null

   • To display the new configuration with the changes added, run:

     # multipath -t

4. Reload the /etc/multipath.conf file and reconfigure the multipathd daemon for changes to take effect:

   # service multipathd reload