Today I received a question around the use of das.failuredetectiontime and das.config.fdm.isolationPolicyDelaySec. Should you be using these advanced settings?
Short answer: no.
Long answer: This myth has been floating around for a long long time. Many people were under the impression that das.failuredetectiontime needed to be configured when you started adding additional isolation addresses.This is not the case!
I just received an email with the question if the same applied to vSphere 5.1 now that "das.config.fdm.isolationPolicyDelaySec" was introduced as a replacement for das.failiredetectiontime. The answer remains "no you should not be using this. Unless, unless there are specific networking requirements to do so. There is absolutely no need to increase the failure detection time / isolation policy delay when multiple isolation addresses are configured. Isolation addresses are pinged in parallel, which means no additional time is needed to complete this process.
In summary, it is not recommended to use these advanced settings unless you have specific networking requirements to do so.