Symantec Corp. Backup Exec has been around for more than a decade. In addition to the core product, there are a lot of add-ons and product-specific agents that can be used in conjunction with Backup Exec. Each of these add-ons has their own set of best practices. Since I can't possibly address all of the best practices for Backup Exec and its various add-ons, I am going to limit my discussion to talking about the best practices for the Advanced Open File Option. Advanced Open File Option is important because without this add-on, any files that are open are skipped and are not backed up, and it's never acceptable to skip backing up a file just because it is open.
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As the name implies, the Advanced Open File Option is a separately licensed add-on that works by taking a point-in-time snapshot of the volume that is being backed up, and then basing the backup on the snapshot.
You should only use the Advanced Open File Option as a generic solution for backing up open files. Some types of data, such as Microsoft Word documents, work really well with snapshot backups. Other types of data, such as databases, can be very problematic. If you attempt to back up an active database using the Advanced Open File Option, there is a chance that your snapshot may capture a partial transaction. If you were to restore such a backup, then you may end up corrupting the database in the process.
If there is a Backup Exec agent that was specifically designed for the type of data that you are backing up (such as Exchange or SQL), then you should use that agent. While it's true that purchasing additional agent licenses will increase the cost of your backup, doing so ensures that your data will be backed up properly. You should use the Advanced Open File Option to backup data types for which no product-specific agent exists.
Configuring Backup Exec Advanced File Option
Backup Exec can be configured so that it automatically uses the Advanced Open File Option module on all volumes. As tempting as it may be to set this as the default option, it is usually best to review each volume individually to see if enabling the Advanced Open File Option module is appropriate for that volume based on the types of data that the volume contains.
Because of the way that the Advanced Open File Option works, it is a good bet that some data is going to change between the time that the backup starts and the time that it ends. At the very least, a few user files may change. However, updates to user files also trigger Master File Table (MFT) updates. This data has to be written somewhere while the volume is frozen for backup. Therefore, you should ensure that a server volume always has enough free space to cache any file changes that may occur during a backup.
Using Symantec Volume Snapshot Provider
If you are using Symantec's Volume Snapshot Provider (VSP), then it is best to reserve a dedicated disk to store the VSP cache. You should not store any other types of data on this disk, and you should not attempt to back the disk up. It is also important to remember that the Advanced Open File Option module won't use this volume for its cache until you tell it to.
It is important to also keep in mind that using the Volume Snapshot Provider isn't going to be an option for every server. If you want to use the Advanced Open File Option module to back up Windows 2000 servers, then using VSP is going to be your only option. Volume Snapshot Provider is also appropriate for use on Windows 2003 servers that were upgraded from Windows 2000. Newer Windows Servers make use of Microsoft's Volume Shadow Copy Service (VSS).
You should also be careful about how volumes are used during backups. Because of the way that snapshots work, you want to try to minimize any changes to volumes while they are being backed up. Otherwise, you could end up overwhelming the snapshot process.
One way that you can accomplish this is to review the settings used by any management software that is used on your servers to make sure that they are not performing any major operations at the same time that the backup is running. For example, it's a good idea to avoid antivirus scans and disk defragmentation while the backup is running.
About the author:
Brien M. Posey, MCSE, has previously received Microsoft's MVP award for Exchange Server, Windows Server and Internet Information Server (IIS). Brien has served as CIO for a nationwide chain of hospitals and was once responsible for the Department of Information Management at Fort Knox. You can visit Brien's personal website at www.brienposey.com.
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