OAM attempts to keep volume catalog entries current. This cannot be accomplished if the catalog entry does not exist or if the catalog is unusable (for example, because of I/O errors). Recovery of the catalog may be required. Standard catalog recovery procedures apply to recovering volume catalogs. Those procedures usually involve making an image copy (for example, IDCAMS EXPORT) at certain intervals and restoring that copy (for example, IDCAMS IMPORT) to recover an unusable catalog, then applying changes to individual records based on some ICF transaction log (for example, SMF records).

If library entries are added or deleted after the image copy is made, restoring an image copy does not complete the recovery; you must also recreate those added or deleted entries. Use IDCAMS CREATE or IDCAMS DELETE to create or to delete the library entries.

If library entries are modified after the image copy is made, use IDCAMS ALTER to update the library entry to its current state.

If volume entries are added or deleted after the image copy is made, restoring an image copy does not complete the recovery; you must also recreate those added or deleted entries. Use IDCAMS CREATE or IDCAMS DELETE to create or to delete the volume entries.

If volume entries are modified after the image copy is made, use IDCAMS ALTER to update the volume entry to its current state.

If you plan to run your disaster recovery test on a system where there is no tape library, then you must EXPORT DISCONNECT the TCDB from that remote system so that normal stand-alone drive allocation paths are used by SMS and MVS allocation. Your ACS routines should also be reviewed and changed, if necessary, to ensure that they are not assigning a tape storage group that forces the allocation to a tape library.

Typically this processing does not require the OAM address space to be started; however, if you are also using OAM object support and need to start the OAM address space, considerations must be given to any tape library definitions that are in the SCDS. Before starting the OAM address space, any tape library definitions associated with the remote system that have an "Initial Online Status" of "YES" or "NO", need to have the initial online status set to blank to indicate that the library is not connected to that system. This enables the OAM address space to bypass those tape library definitions during OAM initialization. However, for that update to be successful, the TCDB needs to be connected. Once the updates have been made, the TCDB can be disconnected and the updated SCDS can be activated.

To better enable disaster recovery (DR) testing, starting with Release 1.7 of the TS7700 Virtualization Engine, the “Selective Write Protect” function allows the library to exclude up to 16 categories from a cluster’s write protect enablement . With this function enabled, only volumes in the specified DR host categories can be modified by the DR host. In addition, the DR host can also mount (for read-only purposes) production scratch volumes (by specific volser) to account for any return to scratch processing that may have occurred on the production systems (the DR host must also have those volumes in private status in the TCDB). The categories excluded from write protect enablement must match those specified in the DEVSUPxx PARMLIB member on the DR host. In addition, the DEVSUPxx categories used by the DR host must be different from those specified on the production hosts. With Selective Write Protect enabled, any volume assigned to one of the specified categories will be excluded from the cluster’s write protect state. The volumes assigned to the excluded categories can be written to or have their attributes modified. Tape management system considerations include setting up the DR host to allow for a new range of logical volumes to be entered and used at the DR host. To assist with this, DFSMSrmm provides volume management capabilities through their PRTITION and OPENRULE commands. For additional information refer to the TS7700 Information Center.