Types of SnapManager restore operations

You can use SnapManager to perform either of the following types of restore operations:

Up-to-the-minute restore operation

In an up-to-the-minute restore, databases are recovered up to the point of failure. SnapManager accomplishes this by performing the following sequence:

The last active transaction log is automatically backed up.
The databases are restored from the full database Snapshot copies you select.
All the transaction logs that were not committed to the databases, from the time the backup set was created up to the most current time, are played forward and applied to the databases (if selected). This includes transaction logs from the backup sets, as well as the existing transaction logs in the transaction log directory.

An up-to-the-minute restore requires a contiguous set of transaction logs. The up-to-the-minute restore type is selected by default. For more information, see Choosing the type of restore operation to perform.

Note
Because SnapManager cannot restore transaction logs from log-shipping backup files, you might not be able to restore the database using an up-to-the-minute restore. For this reason, NetApp recommends that you use SnapManager alone to back up your SQL Server database transaction log files.

Example

Suppose you run SnapManager Backup every day at noon, and on Wednesday at 4 p.m. you need to restore from a backup. For some reason, the backup set from Wednesday lunchtime failed verification, so you decide to restore from the Tuesday lunchtime backup. After that backup is restored, all the transaction logs are played forward and applied to the restored databases, starting with those that were not committed when you created Tuesday's backup set and continuing through the latest transaction log written on Wednesday at 4 p.m.

Point-in-time restore operation

In a point-in-time restore, databases are restored only to a point-in-time from the past. If you choose not to apply any transaction log backup sets, the transaction logs beyond the point-in-time that exist in the transaction log directory belonging to the restored database are removed.

You can also choose to apply a contiguous set of transaction log backup sets. If you apply transaction log backup sets, you can also specify a particular date and time at which you want to stop the application of backed up transactions. To do this, you specify a date and time within the available range and SnapManager will roll back any transactions that were not committed prior to that point in time. You can use this method to restore databases back to a point in time before a corruption occurred. For more information about choosing the restore type, see Choosing the type of restore operation to perform.

Example

Suppose you take full database backups once at midnight and a transaction log backup every hour. The database crashes at 9:45 a.m, but you still back up the transaction logs of the failed database. You can choose from among three point-in-time restore scenarios:

Restore the full database backup taken at midnight and accept the loss of the database changes made afterward.
Restore the full database backup and apply all the transaction log backups until 9:45 a.m.
Restore the full database backup and apply transaction log backup sets. Specifying the time you want the transactions to restore from the last set of transaction log backups.
In this case, you would calculate the date and time where a certain error was reported. Any transactions that were not committed prior to the date and time specified in the Restore command are rolled back.

Note
You can use this method to restore the database up to a point where you think corruption occurred, or to recover from an accidental database or table deletion.

Types of SnapManager restore operations

Related topics

Up-to-the-minute restore operation

Example

Point-in-time restore operation

Example