The copy threshold option (system option mode 467) is an option that temporarily stops the copy process during Volume Migration when the storage system is under heavy load. You can set the copy threshold option (SOM 467) to temporarily stop the copy process during Volume Migration when the storage system is under heavy load, thereby minimizing the degradation of the host I/O performance (response).
However, moving a volume with Volume Migration is more likely to fail if there are more updates from the host to the volume being moved. When the copy threshold option (SOM 467) is turned on, the copy process at the time of Volume Migration is temporarily stopped when the storage system is under heavy load. There is a high probability that migration will fail to move a volume. For this reason, the initial value of this option is ON, but it is recommended that you do not turn it on when there are many updates from the host to the volume that is being moved. For information about setting the copy threshold option (SOM 467), contact customer support.
Note that copy operations that are stopped by the copy threshold option (SOM 467) will resume when the load on the storage system decreases. In addition, if the copy threshold option (SOM 467) is turned on, in addition to Volume Migration, the copy process of the following software products will be stopped when the storage system is overloaded:
- ShadowImage
- ShadowImage for Mainframe
- Compatible FlashCopy® V2