Scaling iControl, race conditions, and other pain points

Unfortunately, the iControl process on the F5 side is pretty much single threaded (it can only process one request at a time). If you have a process that is tying it up for long periods, it will become unresponsive to other processes that are trying to issue iControl commands. In general, it is better to use SNMP in order to gather statistics and only use iControl to issue actual configuration changes/queries. In older versions of code (pre v10.2.2) we had some major inefficiencies in the way we processed SNMP requests that made SNMP pretty unusable for gathering statistics on large numbers of objects at one time. If you are running a pre v10.2.2 TMOS version, you can request an engineering HF that fixes this. Prior to v11.2.0 there were statistics available through iControl that were not available via SNMP. Since v11.2.0, one can create custom MIB entries that enable one to grab anything via SNMP that could be gotten through the command line. The process to do this is described here: http://support.f5.com/kb/en-us/solutions/public/13000/500/sol13596.html?sr=28857189