- Native Multipathing
- Storage Array Type Plug-in (SATP)
- Path Selection Plugin (PSP)
- Third-Party Plug-ins
- Multipathing Plugins (MPPs)
- Anatomy of PSA Components
- I/O Flow Through PSA and NMP
- Listing Multipath Details
- Claim Rules
- MP Claim Rules
- Plug-in Registration
- SATP Claim Rules
- Modifying PSA Plug-in Configurations Using the UI
- Modifying PSA Plug-ins Using the CLI
Figure 5.6 depicts the relationship between third-party plug-ins, NMP, and PSA.
Figure 5.6. Third-party plug-ins
Because PSA is a modular architecture, VMware provided APIs to its storage partners to develop their own plug-ins. These plug-ins can be SATPs, PSPs, or MPPs.
Third-party SATPs and PSPs can run side by side with VMware-provided SATPs and PSPs.
The third-party SATPs and PSPs providers can implement their own proprietary functions relevant to each plug-in that are specific to their storage arrays. Some partners implement only multipathing and failover algorithms, whereas others implement load balancing and I/O optimization as well.
Examples of such plug-ins in vSphere 4.x that are also planned for vSphere 5 are
- DELL_PSP_EQL_ROUTED—Dell EqualLogic PSP that provides the following enhancements:
- Automatic connection management
- Automatic load balancing across multiple active paths
- Increased bandwidth
- Reduced network latency
- HTI_SATP_HDLM—Hitachi ported their HDLM MPIO (Multipathing I/O) management software to an SATP. It is currently certified for vSphere 4.1 with most of the USP family of arrays from Hitachi and HDS. A version is planned for vSphere 5 as well for the same set of arrays. Check with VMware HCL for the current list of certified arrays for vSphere 5 with this plug-in.
See Chapter 8 for further details.