anchor.diff:  
   [source,json]
   {"replica": 0, "freedisk": "<500", "strict" : false}
  +
  +==== Try to Place all Replicas of type TLOG in SSD type file system
  +
  +[source,json]
  +{ "replica": 0,  "sysprop.file_system" : "!ssd",  "type" : "TLOG" }
  +
  +Please note that to use the `sysprop.fs` attribute all your ssd nodes must be started with a system property `-Dfile_system=ssd`.
   
   [[collection-specific-policy]]
   == Defining Collection-Specific Policies
  
positive.code: 
  `sysprop.<system_property_name>`::
  Any arbitrary system property set on the node on startup.
  
  === Policy Operators
  
  
negative.code: `shard`::
  The name of the shard to which the policy rule should apply. If omitted, the rule is applied for all shards in the collection. It supports a special value `#EACH` which means that the rule is applied for each shard in the collection.
  
  `type`::
  The type of the replica to which the policy rule should apply. If omitted, the rule is applied for all replica types of this collection/shard. The allowed values are `NRT`, `TLOG` and `PULL`
  
  `replica`::
  The number of replicas that must exist to satisfy the rule. This must be a positive integer. This is a required attribute.
  
  