Monday, January 24, 2011

dump database three phases

The dump database command makes a copy of the entire
database, including both the data and the transaction log.
dump database does not truncate the log.
dump database allows dynamic dumps. Users can continue to
make changes to the database while the dump takes place.
This makes it convenient to back up databases on a regular
basis.
dump database executes in three phases. A progress message
informs you when each phase completes. When the dump is
finished, it reflects all changes that were made during its
execution, except for those initiated during phase 3."

Phase 1
* Phase 1 is the DBPAGES phase
* The Backup Server scans and dumps all the allocated
pages (both data and log pages) for the given database,
without checking to see whether any of the pages were
updated while this phase is going on.

Phase 2
* Phase 2 is the FLUSHPAGES phase:
* All the data pages that were modified during but not
logged in phase 1 (for example, a fast bcp) are dumped.
* The dump instant is the end of this phase. Recovery
restores the database to the state after phase 2.

Phase 3
* Phase 3 is the SCANLOGPAGES phase:
* The log pages are dumped again to capture
up-to-the-minute changes.
* dump transaction has only one phase: the SCANLOGPAGES
phase.
The dump database command makes a copy of the entire
database, including both the data and the transaction log.
dump database does not truncate the log.
dump database allows dynamic dumps. Users can continue to
make changes to the database while the dump takes place.
This makes it convenient to back up databases on a regular
basis.
dump database executes in three phases. A progress message
informs you when each phase completes. When the dump is
finished, it reflects all changes that were made during its
execution, except for those initiated during phase 3."

Phase 1
* Phase 1 is the DBPAGES phase
* The Backup Server scans and dumps all the allocated
pages (both data and log pages) for the given database,
without checking to see whether any of the pages were
updated while this phase is going on.

Phase 2
* Phase 2 is the FLUSHPAGES phase:
* All the data pages that were modified during but not
logged in phase 1 (for example, a fast bcp) are dumped.
* The dump instant is the end of this phase. Recovery
restores the database to the state after phase 2.

Phase 3
* Phase 3 is the SCANLOGPAGES phase:
* The log pages are dumped again to capture
up-to-the-minute changes.
* dump transaction has only one phase: the SCANLOGPAGES
phase.

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