Specifying  multi  means that Global Mirror starts cycling based on the cycle period, which  defaults to 300 seconds. The valid range is from 60 seconds to 24*60*60 seconds  (86,400 seconds = one day).  If all of the changed grains cannot be copied to the secondary site within the specified time,  then the replication is designed to take as long as it needs and to start the next replication as  soon as the earlier one completes. You can choose to implement this approach by  deliberately setting the cycle period to a short amount of time, which is a perfectly valid  approach. However, remember that the shorter the cycle period, the less opportunity there is  for peak write I/O smoothing, and the more bandwidth you need.  The  -cyclingmode  setting can only be changed when the Global Mirror relationship is in a  stopped state. RPO is the maximum tolerable period in which data might be lost if you switch over to your  secondary volume. If a cycle completes within the specified cycle period, then the RPO is not more than 2x cycle  long. However, if it does not complete within the cycle period, then the RPO is not more than  the sum of the last two cycle times. The current RPO can be determined by looking at the  lsrcrelationship  freeze time attribute.  The freeze time is the time stamp of the last primary Change Volume that has completed  copying to the secondary site. Note the following example:  Remote copy partnerships and relationships do not work reliably if the connectivity on which  they are running is configured incorrectly. This section focuses on the intersystem network,  giving an overview of the remote system connectivity options. The intersystem network is specified in terms of  latency  and  bandwidth . These parameters  define the capabilities of the link regarding the traffic that is on it. They be must be chosen so  that they support all forms of traffic, including mirrored foreground writes, background copy  writes, and intersystem heartbeat messaging (node-to-node communication). Link latency  is the time that is taken by data to move across a network from one location to  another and is measured in milliseconds. The longer the time, the greater the performance  impact. Recovery point objective using Change Volumes 6.3.2 Remote Copy network planning Terminology 1. The cycle period is the default of 5 minutes and a cycle is triggered at 6:00 AM. At 6:03  AM, the cycle completes. The freeze time would be 6:00 AM, and the RPO is 3 minutes. 2. The cycle starts again at 6:05 AM. The RPO now is 5 minutes. The cycle is still running at  6:12 AM, and the RPO is now up to 12 minutes because 6:00 AM is still the freeze time of  the last complete cycle. 3. At 6:13 AM, the cycle completes and the RPO now is 8 minutes because 6:05 AM is the  freeze time of the last complete cycle. 4. Because the cycle period has been exceeded, the cycle immediately starts again. Chapter 6. Copy services  179