Draft Document for Review February 7, 2020 3:15 pm 8464ch09_Oper.fm Figure 9-37 shows creating a cache partition. Figure 9-38 shows an example of the successful creation in the upper half of the window. The  lower half of the window shows an example in which the user failed to observe the amount of  free space that was available in CP0. Figure 9-37 Creating a cache partition Figure 9-38 Example of a success and a failure to create a new partition Notice that redefining the size of existing partitions in an operational TS7700T might create  unexpected load peak in the overall premigration queue, which causes host write throttling to  be applied to the partitions.  For example, consider an example in which a tape attached partition is downsized, and  becomes instantly overcommitted. In this example, the TS7700T premigration queue is  flooded by volumes that got dislodged by the size of this cache partition becoming smaller.  Partition readapts to the new size by migrating volumes in excess to physical tape.  390  IBM TS7700 Release 5.0 Guide