Using Transaction/Archive Logs with Recovered QR Volumes

Overview

The Quick Recovery Agent and the following iDataAgents can work together to provide an integrated data protection and recovery system for your database volumes:

Oracle iDataAgent (Oracle 9.2 on Solaris)
SQL Server iDataAgent

In this scenario, the Quick Recovery Agent creates and maintains a copy, or QR Volume, of the database and log volumes associated with the Oracle or SQL database. The corresponding iDataAgent is then used to back up the associated logs — Transaction Logs for SQL Server and Archive Logs for Oracle.

During a recovery of the QR Volume, the Quick Recovery Agent recovers the database volumes' data as they existed at the point in time of the last QR Volume creation. Any iDataAgent transaction log or archive log backups that were run after the last QR update can then be applied via the corresponding iDataAgent. Additionally for Oracle, if online redo logs are present, they can also be applied to recover the database up to the current time.

This configuration takes advantage of both the speed of recovery offered by the Quick Recovery Agent and the efficiency of log backups (which are typically less resource-intensive than database backups and can be scheduled to occur frequently).

The Oracle iDataAgent provides many options for recovery, and these options need to be selected very carefully. The Oracle database recovery procedures must be followed in the correct sequence; otherwise, data could be lost.

Set Up Data Protection

In order to take advantage of this data protection and recovery system, perform the following:

Create a Subclient in the Quick Recovery Agent containing the database volumes for which you will be creating a QR Volume.
- For Oracle it is strongly recommended that the data files, redo log files, control files, and archive log files reside on different volumes.
Create a QR Volume of the subclient defined in the step above. It is recommended that you schedule incremental updates of the QR Volume. The update interval will determine the point-in-time to which the application volume will be recovered. Therefore, it will likely also affect how frequently transaction logs should be backed up.
- A best practice when using Quick Recovery Agent on SQL Server databases is to run a Full Backup of SQL databases using the SQL Server iDataAgent before creating the QR Volume.
- Unix volumes require that there are no handles present on the destination volumes. Furthermore, the Oracle instances should be in OPEN mode.
Back up the log files using the appropriate application iDataAgent. For this data protection configuration to be useful, backups of the transaction logs should be scheduled to start after the incremental updates of the QR Volume.
- For Oracle, archive logs are backed up as subclient content. This option is accessible at the Oracle iDataAgent subclient level, see Configure Subclient Content. Consider the following:
  - Archive logs should be the only selected content of the subclient. De-select any other contents.
  - It is recommended that you perform one full backup of the data files before backing up logs only.
- For the SQL Server iDataAgent, transaction logs are backed up when you select the Transaction Log backup option. If you did not back up the SQL database in full prior to the volume creation or update, the next SQL Server iDataAgent transaction log backup job after the creation or update is automatically converted to a full backup.

Recover Your Data

Recovering your data for this configuration consists of two tasks:

Recover the QR Volume.

If you are recovering a database volume, you will be asked if you want to leave the database in the Loaded state. If you want to apply logs to the database after the recovery, click Yes. This also applies to Oracle, however selecting Yes will leave the database in the mounted state. In either case, you will not be able to apply logs after the recovery if you click No.
The databases are recovered only to the point of the last QR Volume update. Be sure to restore your logs and/or incremental backups with the appropriate iDataAgent before bringing your database online. See the procedures below.

Restore/Apply the Backed up logs.

For instructions on restoring SQL Server logs, see Apply Transaction Logs to an SQL Database on a Recovered QR Volume.

For information on recovering the database(s) after a Quick Recovery Agent recovery, see:

The Oracle iDataAgent provides many options for recovery and these options need to be selected very carefully. The Oracle database recovery procedures must be followed in the correct sequence or it could result in the loss of data.

Before recovering the Oracle database to a point-in-time, read Caution on the Use of RESETLOGS.