However, if GM operations experience degraded response times from the secondary system  for an extended period, I/O operations begin to queue at the primary system. This queue  results in an extended response time to application hosts. In this situation, the  gmlinktolerance  feature stops GM relationships, and the application host’s response time  returns to normal.  After a  1920  event occurs, the GM auxiliary volumes are no longer in the  consistent_synchronized  state until you fix the cause of the event and restart your GM  relationships. For this reason, ensure that you monitor the system to track when these  1920 events occur. You can disable the  gmlinktolerance  feature by setting the  gmlinktolerance  value to zero.  However, the  gmlinktolerance  feature cannot protect applications from extended response  times if it is disabled. It might be appropriate to disable the  gmlinktolerance  feature under the  following circumstances: A  1920  event indicates that one or more of the SAN components cannot provide the  performance that is required by the application hosts. This situation can be temporary (for  example, a result of a maintenance activity) or permanent (for example, a result of a hardware  failure or an unexpected host I/O workload).  If  1920  events are occurring, it can be necessary to use a performance monitoring and  analysis tool, such as the IBM Virtual Storage Center, to help identify and resolve the  problem. To create an IBM SAN Volume Controller or an IBM Storwize system partnership, use the  mkfcpartnership  command for traditional Fibre Channel (FC or FCoE) connections or  mkippartnership  for IP-based connections. Use the  mkfcpartnership  command to establish a one-way MM/GM partnership between the  local system and a remote system. Alternatively, use  mkippartnership  to create IP-based  partnership. To establish a fully functional MM/GM partnership, you must issue this command on both  systems. This step is a prerequisite for creating MM/GM relationships between volumes on  the IBM Spectrum Virtualize systems. When the partnership is created, you can specify the bandwidth to be used by the  background copy process between the local and remote system. If it is not specified, the  bandwidth default is 50 MBps. The bandwidth must be set to a value that is less than or equal  to the bandwidth that can be sustained by the intercluster link. 562  Implementing the IBM Storwize V5000 Gen2 with IBM Spectrum Virtualize V8.2.1 The svctask mkfcpartnership command 10.9.4 System partnership GLYPH<SM590000> During SAN maintenance windows in which degraded performance is expected from SAN  components, and application hosts can withstand extended response times from GM  volumes. GLYPH<SM590000> During periods when application hosts can tolerate extended response times and it is  expected that the  gmlinktolerance  feature might stop the GM relationships. For example,  if you test by using an I/O generator that is configured to stress the back-end storage, the  gmlinktolerance  feature might detect the high latency and stop the GM relationships.  Disabling the  gmlinktolerance  feature prevents this result at the risk of exposing the test  host to extended response times.