Question on storage SATP

[rickardnobel]

I have some questions on the role of the SATP in ESX/ESXi.

Depeding on what kind of storage you have there will be a certain SATP selected. These SATP are made for the different SAN vendor, for example:

VMW_SATP_EVA

VMW_SATP_EQL

VMW_SATP_CX

VMW_SATP_MSA

VMW_SATP_LSI

VMW_SATP_INV

VMW_SATP_SVC

.

The SATP handles failover if the active path fails, but why is the need for vendor specific failover handling? That is, what is different between the paths for two vendors from the host perspective? Does a path to e.g. an EVA "fail" in a different way or need failover done in a different way than a path to EquaLogic?

Does that SATP "poll" the path to find failures or will it wait passive until the PSP times out and calls the SATP?

[peetz · Accepted solution]

Recently I was on a VMware Customer Support Event were this was discussed, so I have a little insight on this topic now...

I can give a definitive answer to the last question only: The PSP will signal the SATP when it detects a path failure. The SATP won't actively monitor that.

I can also imagine that the vendor specific SATPs exist, because there are vendor specific error codes that are used to signal array malfunctions. These need to be interpreted correctly by the SATP, and they will manifest e.g. in SCSI sense codes that are also partly vendor specific.

Just my thoughts, might be a bit speculative though ...

Andreas

- Check out my VMware Front Experience Blog

[rickardnobel]

I can give a definitive answer to the last question only: The PSP will signal the SATP when it detects a path failure. The SATP won't actively monitor that.

Thanks a lot for the answer!