HP EVA P6550 HP P6300/P6500 EVA User Guide (5697-2486, September 2013) - Page 37

Table 7 Failback preference settings, Table 8 Failback settings by operating system, Table 8

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Table 7 Failback preference settings (continued) Setting Point in time On controller failover On controller failback Path A Failover/Failback At initial presentation On dual boot or controller resynch On controller failover On controller failback Path B Failover/Failback At initial presentation On dual boot or controller resynch On controller failover On controller failback Behavior Otherwise, the units are brought online to Controller 2. All LUNs are brought online to the surviving controller. All LUNs remain on the surviving controller. There is no failback except if a host moves the LUN using SCSI commands. The units are brought online to Controller 1. If cache data for a LUN exists on a particular controller, the unit will be brought online there. Otherwise, the units are brought online to Controller 1. All LUNs are brought online to the surviving controller. All LUNs remain on the surviving controller. After controller restoration, the units that are online to Controller 2 and set to Path A are brought online to Controller 1. This is a one-time occurrence. If the host then moves the LUN using SCSI commands, the LUN will remain where moved. The units are brought online to Controller 2. If cache data for a LUN exists on a particular controller, the unit will be brought online there. Otherwise, the units are brought online to Controller 2. All LUNs are brought online to the surviving controller. All LUNs remain on the surviving controller. After controller restoration, the units that are online to Controller 1 and set to Path B are brought online to Controller 2. This is a one-time occurrence. If the host then moves the LUN using SCSI commands, the LUN will remain where moved. Table 8 (page 37) describes the failback default behavior and supported settings when ALUA-compliant multipath software is running with each operating system. Recommended settings may vary depending on your configuration or environment. Table 8 Failback settings by operating system Operating system HP-UX Default behavior Host follows the unit1 Supported settings No preference Path A/B - Failover only Path A/B - Failover/Failback IBM AIX Auto failback done by the host No preference Path A/B - Failover only Path A/B - Failover/Failback Linux Auto failback done by the host No preference Operating tips and information 37

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Table 7 Failback preference settings
(continued)
Behavior
Point in time
Setting
Otherwise, the units are brought online to
Controller 2.
All LUNs are brought online to the surviving
controller.
On controller failover
All LUNs remain on the surviving controller.
There is no failback except if a host moves the
LUN using SCSI commands.
On controller failback
The units are brought online to Controller 1.
At initial presentation
Path A -
Failover/Failback
If cache data for a LUN exists on a particular
controller, the unit will be brought online there.
On dual boot or controller resynch
Otherwise, the units are brought online to
Controller 1.
All LUNs are brought online to the surviving
controller.
On controller failover
All LUNs remain on the surviving controller.
After controller restoration, the units that are
On controller failback
online to Controller 2 and set to Path A are
brought online to Controller 1. This is a
one-time occurrence. If the host then moves the
LUN using SCSI commands, the LUN will
remain where moved.
The units are brought online to Controller 2.
At initial presentation
Path B -
Failover/Failback
If cache data for a LUN exists on a particular
controller, the unit will be brought online there.
On dual boot or controller resynch
Otherwise, the units are brought online to
Controller 2.
All LUNs are brought online to the surviving
controller.
On controller failover
All LUNs remain on the surviving controller.
After controller restoration, the units that are
On controller failback
online to Controller 1 and set to Path B are
brought online to Controller 2. This is a
one-time occurrence. If the host then moves the
LUN using SCSI commands, the LUN will
remain where moved.
Table 8 (page 37)
describes the failback default behavior and supported settings when
ALUA-compliant multipath software is running with each operating system. Recommended settings
may vary depending on your configuration or environment.
Table 8 Failback settings by operating system
Supported settings
Default behavior
Operating system
No preference
Host follows the unit
1
HP-UX
Path A/B – Failover only
Path A/B – Failover/Failback
No preference
Auto failback done by the host
IBM AIX
Path A/B – Failover only
Path A/B – Failover/Failback
No preference
Auto failback done by the host
Linux
Operating tips and information
37