Vendors Scramble Toward Hot Backup Solutions

Traditionally, backing up corporate databases meant shutting them down. Cold backups are still the simplest means, but only for those actually doing the backup. Everyone who needs access to the most current data residing on that database is essentially out of luck during a cold backup.

Cold backups are safer than hot backups, which write data to tape while the database remains online, but there are disadvantages to cold backups. Dirty data, for instance, is one. During a cold backup, data elements being modified are flagged and the transaction is processed when the database becomes active again. While the database is inactive, though, this method leaves a window of time when the most current data isn’t available.

What with branch offices, mobile workers and sales people all over the world, the need is growing for enterprise-class databases to be running 24x7. "Backup windows are essentially going away. There really is very little time or no time to take a database offline," says John Barry, manager of product marketing, CommVault Systems Inc. (Oceanport, N.J.,, a database backup and recovery solution manufacturer.

CommVault is not the only company that sees value in hot backups. Microsoft Corp. has been scrambling to add hot backup capabilities to SQL Server 7.0, which Microsoft officials recently confirmed will ship at Comdex this fall. "SQL Server 6.5 doesn’t do hot backups," says Chris King, analyst, Meta Group (Burlingame, Calif.). "This is not to say hot backups can’t be done with SQL Server 6.5, but it’s very tricky."

Team Redmond has been working with Hewlett-Packard Co. (HP) and Adaptec Inc. (Milpitas, Calif., to create what the companies refer to as active backup, also known as hot backup or online backup. The software mammoth is tapping in the finishing nails to an active backup utility in SQL Server 7.0. "Microsoft realizes that in order for it to become an enterprise player in the database market, SQL Server 7.0 needs to be infinitely manageable," says King.

The obvious danger of hot backup is system failure. Larry Gray, senior product manager for system performance with HP, says the utility has made provisions for that. "If the system crashes while people are using the database, anything active in memory but not posted to disk is added to the log. The database can see the log and rolls out the transactions when the database is active again," Gray says. Thus, once the database becomes active, the most current data is automatically available.

Microsoft is working on active backup only for SQL Server 7.0. Other companies, such as CommVault, are targeting other databases such as Oracle and Informix. CommVault’s solution is designed for use in corporate networks with more than one vendor’s database. "If you can’t restore [data] how you want it, where you want it, when you want it, in our minds it’s been wasted," says Chris Van Wagoner, marketing manager, CommVault.

CommVault achieves hot backup in a fashion somewhat similar to that of the Microsoft and HP testing method. A separate, dedicated backup server connects to the database server via twin 100Base-T Ethernet connections; Microsoft’s testing scenario used serial connections. Administrators set the system for backup, and it writes to the CommVault central backup server while the database remains active.

Currently, CommVault’s solution, DBVault Magnum, is compatible with both Oracle and Informix databases. CommVault plans to add support for Sybase to DBVault later this year. Also, a version for SQL Server will ship this fall, but that will be a separate product.

With vendors working to create hot backup, this capability is likely to become a norm in database feature sets, but it will not be the only way to back up databases. "Cold backup will still be the preferable method, says Meta Group’s King. "Basically, if the database can be backed up cold, then most people will probably want to do so because it’s much easier. But if there is no window of time where your database can be inaccessible, hot backups will be a solution."

Whether hot backup is used with SQL Server, Oracle, Informix or another database, the new technology enhances the power of Windows NT. "The cost-effectiveness hot backup adds to the Intel/Windows NT combination really extends its use," King says.