Extract-select database recovery mode

Original article-http://technet.microsoft.com/zh-cn/library/ms175987 (SQL .90). aspxhttp: // examples (SQL .90). aspxhttp: // technet.microsoft.com/zh-cn/library/ms1_203 (SQL .90). aspx After switching from simple recovery mode

If you must switch from simple recovery mode to full recovery mode, we recommend that you:

1. After switching to the full or large-capacity log recovery mode, complete database backup or differential database backup is performed immediately to start the log chain.
   Switching to the full or large-capacity log recovery mode takes effect only after the first data backup.
2. Schedule regular log backup and update the restoration plan accordingly.
   Log backup is an indispensable part of the full recovery mode and large-capacity log recovery mode. Log backup allows transaction log truncation. If logs are not often backed up, the transaction logs may be extended until the disk space is fully occupied.

After switching to the simple recovery mode

If you switch from full recovery mode or large-capacity log recovery mode to simple recovery mode, you need to interrupt the backup log chain. Therefore, we strongly recommend that you back up logs before switching, so that you can restore the database to this point. After switching, you need to back up data regularly to protect the data and cut off the inactive part of the transaction log.

 

Switching between full recovery and large-capacity Log Recovery

For databases that use full recovery, switching to the large-capacity log recovery mode temporarily can improve the performance of large-capacity operations. However, if data cannot be lost, we recommend that you switch to the large-capacity log recovery mode to prevent data loss, but only in the following conditions:

• Users are not allowed in the database.
• During the large-capacity processing process, no modifications cannot be restored without relying on log backup; for example, by re-running large-capacity processing.

Suggestion:

• Back up logs before switching to the large-capacity log recovery mode.
  This is very important because in the large-capacity log recovery mode, if the database fails, the data needs to be accessed for the large-capacity operation backup log.
• After performing a large volume operation, immediately switch back to the full recovery mode.
• Back up logs again after switching back to the full recovery mode.

Switching from full recovery or large-capacity Log Recovery to simple recovery

You can switch from full recovery or large-capacity Log Recovery to simple recovery, but this is not common.

Before switching to the simple recovery mode, back up transaction logs to allow recovery to this point. The simple recovery mode does not support log backup. Therefore, after switching, stop all scheduled jobs that back up transaction logs. For more information, see how to change a maintenance task in the maintenance plan wizard.