Understanding VMware Pluggable Storage Architecture


Pluggable storage architecture was one of the major enhancement done by VMware to provide two key functions of the storage component in vSphere world.
• Multipathing: If there are multiple paths, which paths should be used for given I/O
• Failover: When a path goes down, I/O should failover to alternative path automatically.

What is SCSI RESERVATION & How it Works


When single resource is being shared across multiple objects/Users then we need some control mechanism for helping us to avoid any kind of confliction/unnecessary congestion while claiming that resource. That’s what exactly being solved by Reservation.
Reservation restrict other users to claim resource which is already being allocated or used by another user.

What Is ALUA (Asymmetric Logic Unit Access) & How ALUA is different from A/A and A/P Array?


ALUA is type of storage device that is capable of servicing IO to given LUN on two different Storage Processors but in an uneven manner. ALUA is also known as Asymmetric Active/Active Arrays. Active/Active -> Both the Controller ports receives IO Commands to LUN. Asymmetric -> Only one controller which is owning the LUN can issues IO to that LUN.