Closing the Backup Window

Technology that provides a competitive edge for one aspect of business can create problems for another business aspect. For example, consider the array of enterprise-level applications (ELAs) such as customer relationship management (CRM) and enterprise resource planning (ERP). These applications are intended to help companies get a better understanding of their customers and their business operations. However, from another perspective, these applications are simply additional large-scale transaction-processing systems that have data you must store and maintain.

The charm of ELAs is that they're perceived as mission-critical applications. Most companies would be in trouble if all their CRM data disappeared. The growth of ELAs has led to a significant rethinking about storage-backup procedures. As the amount of data that companies need to back up grows, the time necessary to complete backup operations has also increased. Another problem is that as companies move to 24 x 7 operations, the window available to complete backup operations has shrunk.

Backing up more data in less time is only part of the problem. Because captured data is often crucial to the enterprise's operation, storage administrators have to worry about the time intervals between backup procedures. How much data can an organization afford to lose--1 day's worth? 1 hour's worth? 1 minute's worth?

Many typical backup approaches no longer seem suitable. The most traditional backup process is straightforward offline backup. A company might choose specific applications to shut down for a certain period of time while the backup takes place. Unfortunately, offline backup is no longer viable for many applications. An airline reservation system, for example, can never close for a backup process to occur.

Consequently, many applications now support online backup so that the application can keep running as the backup occurs. With an online backup, the database continues to perform read operations, but journals write applications while the backup takes place. The database later updates itself by performing all the write operations that it stored during the backup process.

Although online backup eliminates the need to shut down an application, the process has drawbacks. First, the production database and the backed-up data are never entirely the same. Also, when the backup process is underway, the database is no longer operating in real time.

Over the past several years, large organizations have begun using data-replication technologies to aid in the backup process. With data replication, the system either mirrors all the data to a second storage system or periodically stores snapshots of the data on a second system. Replication, however, is a failover technology, not a substitute for backup procedures. If the database is corrupted, the replicated data is also corrupted.

Recently, companies have begun to offer real-time or windowless backup. Taking advantage of low-cost ATA disk arrays, a backup appliance timestamps and journals each update, creating a virtual view of the data. If a system should crash, the virtual view of the data lets administrators roll back the system to the moment in time just before the crash and restore the data from that point.

According to officials at StorageTek, which has one of the early entries in windowless backup technology, this approach protects data against hardware and software failure, environmental disasters, malicious viruses, and end-user errors such as unintended overwrites and deletes.

Windowless backup is a response to problems created by technologies that are considered solutions in other contexts. Considering its relatively low cost and its harmony with the rise of the concept of data lifecycle management, windowless backup will likely elbow its way into the backup and archiving hierarchy over the next several years.