HP (Hewlett-Packard) B6960-96035 Manual Do Utilizador
1.
A transaction is first recorded into the transaction log.
2.
Changes required in the transaction are then applied to cached pages.
3.
From time to time sets of modified pages are flushed to data files on disk.
Filesystem backup of databases and applications
Databases are constantly changing while they are online. Database servers consist
of multiple components that minimize response time for connected users and increase
performance. Some data is kept in the internal cache memory and some in temporary
log files, which are flushed at checkpoints.
of multiple components that minimize response time for connected users and increase
performance. Some data is kept in the internal cache memory and some in temporary
log files, which are flushed at checkpoints.
Because data in a database can change during a backup, a filesystem backup of
database files makes no sense without putting the database server into a special
mode or even offline. Saved database files have to be in a consistent state, otherwise
the data is of no use.
database files makes no sense without putting the database server into a special
mode or even offline. Saved database files have to be in a consistent state, otherwise
the data is of no use.
The following steps are required to configure a filesystem backup of the database
or application:
or application:
•
identify all data files
•
prepare two programs that are able to shut down and start up the database,
respectively
respectively
•
configure the filesystem backup specification with all the data files included and
specify the shut-down program as a pre-exec command and the start-up program
as a post-exec command
specify the shut-down program as a pre-exec command and the start-up program
as a post-exec command
This method is relatively simple to understand and configure but has one key
disadvantage: the database is not accessible during the backup, which is
unacceptable for most business environments.
disadvantage: the database is not accessible during the backup, which is
unacceptable for most business environments.
Online backup of databases and applications
To overcome the necessity to shut down the database during a backup, database
vendors have prepared interfaces that can be used to put databases temporarily into
special modes to save the data to tapes. Server applications are thus online and
available to users during the backup or restore process. These application-specific
interfaces allow backup products, like Data Protector, to back up or restore logical
units of the database application. The functionality of the backup APIs varies
depending on the database vendor. Data Protector integrations are available for
major databases and applications. For a detailed list of supported integrations, see
the HP Data Protector product announcements, software notes, and references.
vendors have prepared interfaces that can be used to put databases temporarily into
special modes to save the data to tapes. Server applications are thus online and
available to users during the backup or restore process. These application-specific
interfaces allow backup products, like Data Protector, to back up or restore logical
units of the database application. The functionality of the backup APIs varies
depending on the database vendor. Data Protector integrations are available for
major databases and applications. For a detailed list of supported integrations, see
the HP Data Protector product announcements, software notes, and references.
Concepts guide
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