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When a restore of the database is required, the library manager, in conjunction
with the Virtual Tape Server controller performs the following steps when initiated
by a service representative:
1. Each available stacked volume in the library is mounted and the time and
date stamp of the database backup is read. This step finds the most current
database for the stacked volumes in the library.
2. The stacked volume with the most current database is again mounted and
the database in the Virtual Tape Server controller is restored.
3. The Virtual Tape Server then provides information to the library manager to
rebuild its inventory records for each logical volume found in the database.
Once the recovery process has completed, the operator varies the library online at
the recovery site host and the library manager inventory of logical volumes is
uploaded to the host to synchronize the host catalogs (DFSMS and applicable tape
management systems).
At the completion of the recovery process, the Virtual Tape Server and the 3494
library manager will contain database and inventory records and status information
for the logical volumes as found in the most recent database backup on the
undamaged stacked volumes. Depending on the following conditions, some
customer data and logical volumes may not have been recovered:
v The stacked volumes containing the latest database backups were destroyed.
Any changes to the location or status of logical volumes since the last found
database backup are lost. Some logical volume records may be lost. It is
possible, however, that the database will contain the location of the previous use
of logical volumes and that data is accessible to the host.
v One or more stacked volumes found in the restored database were destroyed
during the event.
Although the Virtual Tape Server database and the library manager inventory will
have a record of the logical volumes that resided on the missing stacked
volumes, the data is lost.
v A virtual volume had not been closed at the time of the event.
The Virtual Tape Server database will not have a record of the virtual volume’s
location on a stacked volume and the data is lost.
v Logical volumes were written to a stacked volume between the time the last
database backup was made and the event.
The Virtual Tape Server database will not have a record of the new logical
volume locations on the stacked volume and the data is lost. It is possible,
however, that the database will contain the location of the previous use of the
logical volume and that data is accessible to the host.
Chapter 8. Problem Determination Procedures 303