I am often questioned during my Storage for Virtual Environments seminar presentations about VMware’s Pluggable Storage Architecture (PSA). This system is fairly straightforward and concept: VMware provides native multipathing support for a variety of storage arrays, and allows third parties to substitute their own plug-ins at various points in the stack. But the profusion of acronyms and third-party options makes it difficult for end-users to figure out what is going on.
Multipath: Active/Passive, Dual Active, and Active/Active
Although it’s rare in the PC world, multipath I/O is not new in enterprise IT. I’ve been juggling paths to storage and networks as long as I’ve been a systems administrator, and that’s a bit longer than I care to admit. But the proliferation of technologies has made it difficult to understand path management. What’s the difference between “dual active” and “active/active”? Is “active/passive” really that bad?