TotalStorage Productivity Center Database Backup Considerations
Published 27 June 2007
Authors: Mary Lovelace
This Technote describes the high-level points you need to understand about DB2 UDB before
you can plan a backup strategy for securing TotalStorage Productivity Center Version 3.
This section describes the high-level points you need to understand about DB2 UDB before you can plan a backup strategy for securing TotalStorage Productivity Center.
There are two primary methods of backing up DB2 databases:
- Offline backup (sometimes known as cold backup) is when all database access is terminated and the database is closed. The backup then runs standalone before the database is restarted and access is enabled. This is the simplest type of backup to set up and maintain.
- Online backup (sometimes known as hot backup) is when all user and application database access continues to run while the backup process occurs. This type of backup provides for continuous availability of the database and applications that require it. This is a more complex type of backup to set up and maintain.
Backup Output Destination
Database backups' output can be directed to a number of destinations from within DB2:
- Filesystem - Output is directed to normal filesystem structure flat files. These files can then be copied to removable tape for added security or backed up by products such as Tivoli Storage Manager or other widely available similar tools.
- Tape - Output is sent directly to tape if such a device is directly attached to the server hardware.
- TSM - Output is sent directly to Tivoli Storage Manager through direct integration between the two products. If a Tivoli Storage Manager environment exists within your organization you can backup directly to it by installing the Tivoli Storage Manager Backup/Archive client and client API on the same machine that hosts the TPC DB2 databases.
- XBSA - Output is directed to an XBSA (X/Open Backup Services Application) compliant application such as Legato NetWorker.
- Vendor DLL - Output is directed to a third-party vendor written interface API.
DB2 UDB uses log files to keep a sequential record of all database changes. They are specific to DB2 UDB activity. The logs record the database activity in transactions. If there is
a crash, logs playback or redo committed transactions during recovery. There are the following two kinds of logging:
- Circular logging (default) - This is the simplest method and the default logging type used by TotalStorage Productivity Center.
- Archive logging - This type of logging enables online backup as well as roll-forward recovery of a database to a point-in-time. It is however more complex to manage.
Database backup method considerations
This section considers the merits of offline verses online backup methods for the TotalStorage Productivity Center databases. The default method of backup for TotalStorage
Productivity Center is to use offline backup.
Offline backup pros
- Simple - Offline backup can be performed with DB2 logging set to the default circular method.
- DB2 Skills - Being the simplest method means that offline backup requires a minimum amount of skills in DB2 to perform.
- Logging - Circular logs are the simplest to manage and maintain.
Offline backup cons
- Stop TPC Server- The offline method entails stopping all of the TotalStorage Productivity Center Server services on a regular basis (typically daily) to perform the backup. This regular outage may not be acceptable to all organizations wanting to use TotalStorage Productivity Center.
- Miss Performance Data Collection - If you set up TotalStorage Productivity Center to continuously collect disk subsystem and SAN fabric performance statistics, data points are lost for the duration that TPC is down each day for backup. The impact of this can be minimized by scheduling the backup at a time when the monitored equipment statistics are of little importance from a reporting perspective. This may not be acceptable to all organizations wanting to use TotalStorage Productivity Center.
- Miss Events - TotalStorage Productivity Center monitors the infrastructure and alert on events such as failures within a SAN fabric. You run the risk that critical events could be missed if they occur when the TotalStorage Productivity Center server services are stopped for the backup process.
Online backup pros
- Greater Availability - The TotalStorage Productivity Center Server services do not need to be stopped and started on a daily basis for the backup operation. Online backups do not interrupt user access to the database while the backup operation is in progress.
- No Events Missed - TotalStorage Productivity Center monitors the infrastructure and alert on events such as failures within a SAN fabric. Using online backup ensures that TotalStorage Productivity Center can respond quickly to critical events at any time of the day.
- Uninterrupted Performance Collection - There is no interruption or missing data points in the collection of performance data from disk subsystems and SAN fabrics.
- More DB2 Skills Required - Archive logging should be considered a more advanced method of DB2 operation and as such requires more skills to administer it.
- TPC Software Update process can fail - Our testing found that TPC software updates that alert the database layout can fail. You need to revert to circular logging to perform updates, and then switch back to archive logging.
In the book we focus on file system and Tivoli Storage Manager as backup destinations. The procedures we used are documented in detail.
This material has not been submitted to any formal IBM test and is published AS IS. It has not been the subject of rigorous review. IBM assumes no responsibility for its accuracy or completeness. The use of this information or the implementation of any of these techniques is a client responsibility and depends upon the client's ability to evaluate and integrate them into the client's operational environment.
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