In vSphere 4, when multiple Multipathing Plugins (MPPs) exist, the Pluggable Storage Architecture (PSA) performs which of the following three tasks (Choose Three)?
A.
I/O queuing to the physical storage HBAs
B.
Association of physical paths with logical devices
C.
Management tasks such as abort or reset of logical devices
D.
Physical path discovery and removal
E.
I/O queuing to the logical devices
Explanation:
What is Pluggable Storage Architecture (PSA) and Native Multipathing (NMP)?Pluggable Storage Architecture (PSA)
PSA is a collection of VMkernel APIs that allow third party hardware vendors to insert code directly into the ESX storage I/O path. This allows 3rd party software developers to design their own load balancing techniques and failover mechanisms for particular storage array.The PSA coordinates the operation of the NMP and any additional 3rd party MPP.
Native Multipathing Plugin (NMP)
VMware provides a generic Multipathing Plugin (MPP), called Native Multipathing Plugin (NMP).
What does NMP do?* Manages physical path claiming and unclaiming.
* Registers and de-registers logical devices.
* Associates physical paths with logical devices.
* Processes I/O requests to logical devices:
o Selects an optimal physical path for the request (load balance) [B above]
o Performs actions necessary to handle failures and request retries.
* Supports management tasks such as abort or reset of logical devices.[C above] Since the NMP provides B and C, the PSA must perform A, D and E