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A.3.2. Configure Multipath

On each R710, exclude the local disks from the control of multipathd.

1. Make sure the multipath software is installed. To verify if the multipath software is installed:

# rpm –a | grep multipath

device-mapper-multipath-0.4.9-41.el6.x86_64

device-mapper-multipath-libs-0.4.9-41.el6.x86_64

If the packages are not present, install them and then run the following command to create the

/etc/multipath.conf file:

#/sbin/mpathconf --user_friendly_names y

Alternatively, copy the example included in the multipath package to /etc/multipath.conf:

# cp –p /usr/share/doc/device-mapper-multipath-0.4.9/multipath.conf

/etc/multipath.conf

2. Make sure the service multipathd is not started.

#service multipathd status

Multipathd is stopped

Otherwise, local disks will be controlled by the multipathd service and that will prevent stopping

or restarting the service, with the following message:

Root is on a multipathed device, multipathd cannot be stopped

3. Blacklist local devices to prevent problems when installing MDSM later in section A.3.4.

a. Identify the local virtual disks created in section A.2.

# parted -l 2>&1 |grep -A1 -B1 'Model: DELL PERC H700'

Model: DELL PERC H700 (scsi)

Disk /dev/sda: 146GB

Model: DELL PERC H700 (scsi)

Disk /dev/sdb: 292GB

Note: Virtual disks (RAID 0 and 1) devices are listed as PERC devices, hard disks not part of a RAID

device will be shown under the hard disk manufacturer and model number, so the above command

will not list them. If that is the case, make sure multipathd is not enabled (chkconfig

multipathd off), reboot and enter the PERC H700 controller BIOS to create the virtual disks,

reboot again and continue from the previous step.

b. Get the WWID of those local devices.

# /sbin/scsi_id --whitelisted --device=/dev/sda

36842b2b0723e980017184fb50ae00d6a

# /sbin/scsi_id --whitelisted --device=/dev/sdb

36842b2b0723e980017184fcf0c6c56e9