Technical data

Example 3. Failover and Failback
If group A has sdad and sdo,andgroupB has sdj and sdy, the failover occurs from group A to group
B and the failback occurs from group B to group A .
The state of the path is given as [ready] [active] if the path is up, and ready for I/O. If the path is d own,
this state is shown as [faulty] [failed]. The path states are updated periodically based on the polling
interval set in the /etc/multipath.conf file. The path states are updated by the multipathd
daemon.
Table 4 lists the basic operations supported by the multipath CLI utility provided with HPDM M ultipath.
Table4BasicoperationsofHPDMMultipath
Command Description
# multipath –F
Deletes all HPDM Multipath devices.
# multipath –d
Displays potential paths, but does not create any device.
# multipath
Creates HPDM Multipath devices.
# multipath
-l
# multipath
-ll
Displays the list of device status.
Displays the detailed list of device status.
# multipath –v2 <device>
Configures and displays multipath map information.
# multipath –v3
Configures and displays multipath map information.
Clustering Solutions with HPDM Multipath
HPDM Multipath supports the following clustering solutions:
• HP Serviceguard for Linux version 11.18 or later
• SteelEye L
ifeke eper for Linux version 6.1.4 or later
Configuring HP Service Guard with HPDM Multipath Devices
HPDM Multipath devices can be used for data storage under Serviceguard protection. To configure
HPDM Multipath de vices under Serviceguard, complete the following steps:
1. Configure the SAN such that ea ch host has multiple paths to the array. Present the LUN’s to all
the hosts.
2. See Configuring HPDM Multipath for configuring the LUN’s for HPDM Multipath
3. Use the HPDM Multipath device to create the logical volumes that are used by Serviceguard
for Linux.
Please refer the HP ServiceGuard Compatibility matrix for the suppor ted Operating Systems and the
Arrays.
NOTE:
HPDMMultipathdevicescanbeusedwithHPServiceguardA.11.18forLinux.TheLVMvolumegroups
must be configuredontheHPDMMultipathdevices.InHPServiceGuardpackageconfiguration, the
disk monitor must be configured using the HPDM Multipath dev ice in the format /dev/dm-x. Please
ensure that the device names (/dev/dm-x) are same across all the nodes. Configuration requirements HP
Serviceguard for Linux are available in the certification matrix available at the following website:
h
ttp://www.hp.com/info/sglx
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Using H PDM Multipath