The ALTER SYSTEM SUSPEND statement suspends a database by halting all input and output (I/O) to datafiles (file header and file data) and control files, thus allowing a database to be backed up without I/O interference. When the database is suspended all preexisting I/O operations are allowed to complete and any new database accesses are placed in a queued state.
The suspend command suspends the database, and is not specific to an instance. Therefore, in an Oracle Real Application Clusters environment, if the suspend command is entered on one system, then internal locking mechanisms will propagate the halt request across instances, thereby quiescing all active instances in a given cluster. However, do not start a new instance while you suspend another instance, since the new instance will not be suspended.
Use the ALTER SYSTEM RESUME statement to resume normal database operations. You can specify the SUSPEND and RESUME from different instances. For example, if instances 1, 2, and 3 are running, and you issue an ALTER SYSTEM SUSPEND statement from instance 1, then you can issue a RESUME from instance 1, 2, or 3 with the same effect.
The suspend/resume feature is useful in systems that allow you to mirror a disk or file and then split the mirror, providing an alternative backup and restore solution. If you use a system that is unable to split a mirrored disk from an existing database while writes are occurring, then you can use the suspend/resume feature to facilitate the split.
The suspend/resume feature is not a suitable substitute for normal shutdown operations, however, since copies of a suspended database can contain uncommitted updates.
Do not use the ALTER SYSTEM SUSPEND statement as a substitute for placing a tablespace in hot backup mode. Precede any database suspend operation by an ALTER TABLESPACE BEGIN BACKUP statement.
The following statements illustrate ALTER SYSTEM SUSPEND/RESUME usage. The V$INSTANCE view is queried to confirm database status.
SQL> ALTER SYSTEM SUSPEND;
System altered
SQL> SELECT DATABASE_STATUS FROM V$INSTANCE;
DATABASE_STATUS
———
SUSPENDED
SQL> ALTER SYSTEM RESUME;
System altered
SQL> SELECT DATABASE_STATUS FROM V$INSTANCE;
DATABASE_STATUS
———
ACTIVE
The suspend command suspends the database, and is not specific to an instance. Therefore, in an Oracle Real Application Clusters environment, if the suspend command is entered on one system, then internal locking mechanisms will propagate the halt request across instances, thereby quiescing all active instances in a given cluster. However, do not start a new instance while you suspend another instance, since the new instance will not be suspended.
Use the ALTER SYSTEM RESUME statement to resume normal database operations. You can specify the SUSPEND and RESUME from different instances. For example, if instances 1, 2, and 3 are running, and you issue an ALTER SYSTEM SUSPEND statement from instance 1, then you can issue a RESUME from instance 1, 2, or 3 with the same effect.
The suspend/resume feature is useful in systems that allow you to mirror a disk or file and then split the mirror, providing an alternative backup and restore solution. If you use a system that is unable to split a mirrored disk from an existing database while writes are occurring, then you can use the suspend/resume feature to facilitate the split.
The suspend/resume feature is not a suitable substitute for normal shutdown operations, however, since copies of a suspended database can contain uncommitted updates.
Do not use the ALTER SYSTEM SUSPEND statement as a substitute for placing a tablespace in hot backup mode. Precede any database suspend operation by an ALTER TABLESPACE BEGIN BACKUP statement.
The following statements illustrate ALTER SYSTEM SUSPEND/RESUME usage. The V$INSTANCE view is queried to confirm database status.
SQL> ALTER SYSTEM SUSPEND;
System altered
SQL> SELECT DATABASE_STATUS FROM V$INSTANCE;
DATABASE_STATUS
———
SUSPENDED
SQL> ALTER SYSTEM RESUME;
System altered
SQL> SELECT DATABASE_STATUS FROM V$INSTANCE;
DATABASE_STATUS
———
ACTIVE
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