thinQmaster Virtual testing partner Adaptive practice exams that find your weak spots and drill them. Every answer explained. From $69
Enroll

thinQmaster

Find your exam

Five questions free, before you decide.

Step 1 · choose a vendor

In one of our camps? Your practice exams come with the tuition — they are on your study page already.

Systems & Data Center · Advanced

Asymmetric Logical Unit Access (ALUA)

A SCSI standard by which a storage array reports which paths to a LUN are active-optimized versus active-non-optimized.

Definition

In dual-controller arrays, the controller owning a LUN offers optimized paths. Multipathing software prefers those paths and uses non-optimized paths only on failure.

Example

VMware's round-robin PSP sends I/O only across active-optimized paths reported via ALUA.

Exam tip

Sending I/O on non-optimized paths causes extra latency through the inter-controller link.

Related terms