ZK servers currently enforce a min/max boundary on client session timeout relative to the ticktime setting, detailed here:
In general there are good reasons for this however in some cases, in particular with HBase region servers, we have seen a need to allow this bound to be set differently (higher). The Sun jvm can GC pause for very long times (in some cases we've seen 4 minutes even with the "realtime" gc.
It would be good to allow this bound to be set via configuration parameters.
Note: 4letterword and JMX integration would be needed.