Soft Fence

DS8870 disk subsystems can provide a Soft Fence function. The purpose of this function is to prevent unintended access to a device in a logical subsystem (LSS). Most I/O operations (like reading and writing data) to a device are prevented by the disk subsystem if the Soft Fence state is set for the device (the device is soft fenced).

TDMF supports this function by resetting a possible Soft Fence state for target devices at the beginning of a migration session and by setting the Soft Fence state for migration source devices as soon as they have been swapped with their associated target devices. Supporting source devices are put into the Soft Fence state by default in order to prevent any unintended and undetected access to original source volumes after they have been migrated as this may cause data integrity issues.

Important: If the device was previously FlashCopy enabled and has been put into the Soft Fence state, FlashCopy will be disabled. If the device is to be re-used in a GDPS PPRC environment, then FlashCopy will need to be re-enabled before use. Once Soft Fence has been disabled with ICKDSF, FlashCopy can be re-enabled through the following actions:
  1. GTDCLUP PARM=FLASHCOPY
  2. Console command DS DIAG,uuuu,nn,ALLOWFC