Chapter 3. Setting Up DM-Multipath
8
service multipathd start
multipath -v2
The
multipath -v2
command prints out multipathed paths that show which devices are
multipathed. If the command does not print anything out, ensure that all SAN connections are set
up properly and the system is multipathed.
For further information on the
multipath
command output, see
Section 5.5, “Multipath
Command Output”
.
5. Execute the following command to ensure sure that the multipath daemon starts on bootup:
chkconfig multipathd on
Since the value of
user_friendly_name
is set to
yes
in the configuration file the multipath devices
will be created as
/dev/mapper/mpath
n
. For information on setting the name of the device to an
alias of your choosing, see
Chapter 4, The DM-Multipath Configuration File
.
3.2. Ignoring Local Disks when Generating Multipath
Devices
Some machines have local SCSI cards for their internal disks. DM-Multipath is not recommended for
these devices. The following procedure shows how to modify the multipath configuration file to ignore
the local disks when configuring multipath.
1. Determine which disks are the internal disks and mark them as the ones to blacklist.
In this example,
/dev/sda
is the internal disk. Note that as originally configured in the default
multipath configuration file, executing the
multipath -v2
shows the local disk,
/dev/sda
, in
the multipath map.
For further information on the
multipath
command output, see
Section 5.5, “Multipath
Command Output”
.
[root@rh4cluster1 ~]#
multipath -v2
create: SIBM-ESXSST336732LC____F3ET0EP0Q000072428BX1
[size=33 GB][features="0"][hwhandler="0"]
\_ round-robin 0
\_ 0:0:0:0 sda 8:0
[---------
device-mapper ioctl cmd 9 failed: Invalid argument
device-mapper ioctl cmd 14 failed: No such device or address
create: 3600a0b80001327d80000006d43621677
[size=12 GB][features="0"][hwhandler="0"]
\_ round-robin 0
\_ 2:0:0:0 sdb 8:16
\_ 3:0:0:0 sdf 8:80
create: 3600a0b80001327510000009a436215ec
