Documentation< Previous | Contents | Next >
3.1. Setting Up DM-Multipath
Before setting up DM-Multipath on your system, ensure that your system has been updated and includes the multipath-tools package. If boot from SAN is desired, then the multipath-tools-boot package is also required.
A basic /etc/multipath.conf need not even exist, when multpath is run without an accompanying /etc/ multipath.conf, it draws from it's internal database to find a suitable configuration, it also draws from it's internal blacklist. If after running multipath -ll without a config file, no multipaths are discovered. One must proceed to increase the verbosity to discover why a multipath was not created. Consider referencing the SAN vendor's documentation, the multipath example config files found in /usr/share/doc/multipath-tools/ examples, and the live multipathd database:
# echo 'show config' | multipathd -k > multipath.conf-live
To work around a quirk in multipathd, when an /etc/multipath.conf doesn't exist, the previous command will return nothing, as it is the result of a merge between the /etc/multipath.conf and the database in memory. To remedy this, either define an empty /etc/multipath.conf, by using touch, or create one that redefines a default value like:
defaults {
user_friendly_names no
}
and restart multipathd:
# systemctl restart multipath-tools.service
Now the "show config" command will return the live database.