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ALUA support and requirements

Data ONTAP uses ALUA (asymmetric logical unit access) to identify optimized paths. ALUA is required for specific configurations.

ALUA is an industry-standard protocol for identifying optimized paths between a storage system and a host. ALUA enables the initiator to query the target about path attributes, such as primary path and secondary path. It also allows the target to communicate events back to the initiator.

ALUA must be enabled for specific configurations.

Windows version Protocol Data ONTAP version ALUA supported and required?
Windows Server 2003 iSCSI 7-Mode No
Clustered Data ONTAP Yes
Fibre Channel 7-Mode Yes
Clustered Data ONTAP Yes
Windows Server 2008 iSCSI 7-Mode No
Clustered Data ONTAP Yes
Fibre Channel 7-Mode Yes
Clustered Data ONTAP Yes
Windows Server 2012 iSCSI 7-Mode No
Clustered Data ONTAP Yes
Fibre Channel 7-Mode Yes
Clustered Data ONTAP Yes
Windows Server 2012 R2 iSCSI 7-Mode Yes
Fibre Channel Clustered Data ONTAP Yes

ALUA support is enabled or disabled on the igroup or igroups to which a LUN is mapped. All igroups mapped to a LUN must have the same ALUA setting. Windows detects a change to the ALUA setting when rebooted.

ALUA is enabled by default on clustered Data ONTAP igroups. In some situations, ALUA is not automatically enabled on 7-Mode igroups.

Note: Data ONTAP does not support ALUA on single-controller storage systems. Even though ALUA is not supported, the Data ONTAP DSM supports paths to single-controller storage systems. The DSM identifies paths to single-controller storage systems as active/optimized.