Auto Mode and Manual Mode (Using CREATE SHADOW)
Go Up to Using CREATE SHADOW
A shadow can become unavailable for the same reasons a database becomes unavailable: disk failure, network failure, or accidental deletion. If a shadow becomes unavailable, and it was created in AUTO mode, database operations continue automatically without shadowing. If a shadow becomes unavailable, and it was created in MANUAL mode, further access to the database is denied until the database administrator intervenes. The benefits of AUTO mode and MANUAL mode are compared in the following table:
| Mode | Advantage | Disadvantage |
|---|---|---|
|
|
Database operation is uninterrupted |
Creates a temporary period when the database is not shadowed; the DBA might be unaware that the database is operating without a shadow. |
|
|
Prevents the database from running unintentionally without a shadow |
Halts database operation until the problem is fixed; needs intervention of the DBA |