Support for logical WORM is provided with Release 1.6 of the TS7700 Virtualization Engine (for both the TS7740 and the TS7720). Refer to APAR OA28632 (z/OS V1R9 and above) for additional detail. If the TS7700 is a multi-cluster grid, all clusters in the grid must be at a release level that supports logical WORM for the TS7700 to be WORM enabled. To request a logical WORM volume, an outboard data class policy must be defined (at the library) requesting logical WORM. This data class must then be assigned through the ACS routines, for a logical WORM request. A logical volume will become WORM when it is first mounted and written from load point. A volume will not take on the WORM attribute if user data had already been written to the volume. Also, when a dataset written to a WORM volume extends to another volume (EOV processing), the next volume in the chain will also be WORM. This is handled through the existing advanced (outboard) policy management support. As with the 3592 physical WORM tape support, any attempt by the host to modify a previously written user data record of a logical WORM volume will be failed by the TS7700.
With the 3592 WORM tape support, a volume is designated as WORM through usage of special WORM media types (MEDIA6, MEDIA8, MEDIA10, and MEDIA12). A logical volume (MEDIA1 or MEDIA2) will be designated as WORM, not by the usage of a special WORM media type, but when it is first mounted and written from load point (and associated with a data class policy that has WORM functionality enabled at the library). As a result, a common scratch pool is used for both rewritable (R/W) and WORM requests and when a logical volume (R/W or WORM) is returned to scratch it can be reused on a scratch (category) mount as either rewritable (R/W) or as WORM. As with the 3592 WORM tape support, a logical WORM volume is assigned a world-wide unique identifier (WWID) and is associated with a write mount count (WMC). During the mount, the TS7700 assigns a WWID and WMC to the volume.
Once a logical WORM volume has expired, to be consistent with physical WORM and the special release actions that may be in place by the tape management system, for the logical volume’s VOLSER to be reused, it must be returned to scratch and the reuse of the volume (as either WORM or rewritable (R/W)) must then occur as a scratch (category) mount. If the volume is subsequently reused as logical WORM, the library will create a new WWID and WMC for this new instance of the volume. If, instead, the expired WORM volume’s VOLSER is to be reused (from load point) by specific mount (and not by scratch mount), the volume must first be moved to scratch and ejected “purged” from the library. At that time, the volume can then be entered (as a new logical volume) into the library as private and used as either WORM or rewritable (R/W). Also, once a previously used R/W volume has expired, to be reused as logical WORM, it must also go through the logical WORM steps above if the volume is to be mounted by specific VOLSER (and not by scratch mount). In summary, a logical volume can become WORM when it is mounted as a scratch volume (category mount) or mounted by specific volser and the volser referenced is considered a new logical volume. Refer to your tape management system for its usage of the WWID and the WMC and for its handling of expired logical WORM volumes.