If checked, all calls to the AccuRev CLI on a particular node will be synchronized. That is to say, only one CLI operation can be going on at any time, across all jobs on a given node. The default is synchronized, which is the plugin's original behavior.

Note that login operations are always synchronized.

This sync was supposedly for problems with older versions of the AccuRev CLI. If you have a recent version of AccuRev (4.7+, possibly earlier), but are using "traditional" authentication, it should be ok to turn off synchronization. This can speed up operations significantly in some scenarios, such as with multiple jobs with large checkouts. If you are using "accurev_login" or "custom" authentication, even on recent versions of AccuRev (e.g. 4.7.4 suffers from this), you need to ensure that you never run a "login" unless no other AccuRev operations are ongoing, otherwise those other AccuRev operations are likely to fail.