Automatic File Movement and Erasure by DFSMS/VM

You should be aware that DFSMS/VM can automatically cause SFS files to be placed in migrated status (that is, move the file data into its storage repository) or erased at certain predetermined times, without advance warning, according to your installation's storage management policies. (Files in directory control directories may be erased.) File erasure criteria are usually related to how long the file has existed, or the length of time since it has last been referenced. The entire file may be erased, or only the data in the file. See z/VM: DFSMS/VM Storage Administration for more information about DFSMS/VM.