There are three models for backing up applications:
- The application maintains a transaction log for each transactional
unit of work. A backup can be taken any time the application is running.
If the data is recovered, the transaction log can be used to either
back out, or redo, the transactions to reach a known sync point for
the application.
- The application provides a quiesce capability, during which time
transactional updates are suspended.
- The application does not provide either a transaction log or quiesce
capability. In this simplest case, it is suggested that the backups
occur only when the files are closed. If backups are taken while the
files are open, it might be difficult to determine which transactions
were fully recorded, and which others were still in flight.
IBM® offers three ways to
perform backups and maintain an inventory of their attributes:
- DFSMShsm
- Tivoli® Storage Manager,
formerly known as ADSTAR Distributed Storage Manager (ADSM)
- DFSMSdss