What is ALUA?

Dear Axe,

Asymmetric Logical Unit Access (ALUA) is a multi-target port access model. In a multipathing state, the ALUA model provides a way of presenting active/passive LUNs to a host and offers a port status switching interface to switch over the working controller. For example, when a host multipathing program that supports ALUA detects a port status change (the port becomes unavailable) on a faulty controller, the program will automatically switch subsequent I/Os to the other controller.

ALUA is applicable to a storage system that has only one prior LUN controller. All host I/Os can be routed through different controllers to the working controller for execution. ALUA will instruct the hosts to deliver I/Os preferentially from the LUN working controller, thereby reducing the I/O routing-consumed resources on the non-working controllers.

If all I/O paths of the LUN working controller are disconnected, the host I/Os will be delivered only from a non-working controller and then routed to the working controller for execution.

Thanks.

Dar Friend:

ALUA
ALUA definition:
Asymmetric Logical Unit Access (ALUA) is a multi-target port access model. In a multipathing state, the ALUA model provides a way of presenting active/passive LUNs to a host and offers a port status switching interface to switch over the working controller. For example, when a host multipathing program that supports ALUA detects a port status change (the port becomes unavailable) on a faulty controller, the program will automatically switch subsequent I/Os to the other controller.

ALUA impacts:
ALUA is mainly applicable to a storage system that has only one prior LUN controller. All host I/Os can be routed through different controllers to the working controller for execution. ALUA will instruct the hosts to deliver I/Os preferentially from the LUN working controller, thereby reducing the I/O routing-consumed resources on the non-working controllers.

If all I/O paths of the LUN working controller are disconnected, the host I/Os will be delivered only from a non-working controller and then routed to the working controller for execution.

https://support.huawei.com/enterprise/en/doc/EDOC1000162774/9c375fd6/multipath-connectivity#EN-US_TOPIC_0115812044

Thanks!