I had a question this week what Misc SIOControlFlag2 was. Some refer to it as SIOControlFlag2 and I’ve also seen Misc.SIOControlFlag2. In the end it is the same thing. It is something that sometimes pops up in the log files, or some may stumble in to the setting in the “advanced settings” on a host level. The question I had was why the value is 0 on some hosts, 2 on others or even 34 on other hosts.
Let me start with saying that it is nothing to worry about, even when you are not using Storage IO Control. It is an internal setting which is used by ESXi (hostd sets it) when there is an operation done where disk files on a volume are opened (vMotion / power on etc). This is set to ensure that when Storage IO Control is used that the “SIOC injector” knows when to or when not to use the volume to characterize it. Do not worry about this setting being different on the hosts in your cluster, it is an internal setting which has no impact on your environment itself, other then when you use SIOC this will help SIOC making the right decision.
Irfan Ahmad says
Indeed. Very embarrassing to admit that this was a hack our team put in to get around limitations of the ESXi interprocess configuration synchronization. At the time, it was supposed to be for one release only, to be ripped out in ESXi 5 when a new “registry-like” mechanism was to be introduced. Unfortunately, funding for that proper mechanism was pulled and this hack remains to this day.
Like Duncan correctly states, this is to be ignored.