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4.2.2. Blacklisting By Device Name

You can blacklist device types by device name so that they will not be grouped into a multipath device by specifying a devnode entry in the blacklist section of the configuration file.
The following example shows the lines in the configuration file that would blacklist all SCSI devices, since it blacklists all sd* devices.
blacklist {
       devnode "^sd[a-z]"
}
You can use a devnode entry in the blacklist section of the configuration file to specify individual devices to blacklist rather than all devices of a specific type. This is not recommended, however, since 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, the following devnode entries are compiled in the default blacklist; the devices that these entries blacklist do not generally support DM-Multipath. To enable multipathing on any of these devices, you would need to specify them in the blacklist_exceptions section of the configuration file, as described in Section 4.2.4, “Blacklist Exceptions”.
blacklist {
       devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st)[0-9]*"
       devnode "^(td|hd)[a-z]"
}