UP FRONT: From the Editor
Available and WorkingBy Tom Haunert
Inexpensive resources for high availability improve enterprise performance.
At 5 p.m. on October 17, 1989, I was ending my workday in the San Francisco Bay Area, backing up my PC data to tape. A few minutes after 5 p.m., my tape backup still in progress, a major earthquake hit the area. There were fatalities, and bridges, roadways, and homes collapsed. At my office the damage was minor—it included shattered windows and a power outage.
Power was restored to the office the next morning, and when I went back into work, my focus shifted from trying to find out if my friends and family were OK after the quake (they were) to seeing if I still had a working PC, a working tape backup, and the data I had been trying to preserve.
PC hardware in 1989 was not nearly as reliable as it is today, and for its capabilities, it was also quite expensive. Some of my concern about my PC came from my company; I worked at a PC hardware company that consistently warned its customers—and employees—that interrupting power to disk and tape drives while they were operating could cause permanent drive failure.
Luckily my hardware and data survived. I did not need to recover data from an earlier backup—but I was certainly glad that I had an archive of tape backups, just in case—and didn't need to requisition expensive new hardware.
DBAs and system administrators deal with backup and recovery in much more reliable and sophisticated ways than I did in on my old desktop PC. Tape and disk backups are centrally managed and widely used, and powerful backup and recovery capabilities are giving DBAs opportunities to recover data without ever going to the backup tapes.
Oracle Flashback technologies, for example, including Flashback Query, Flashback Table, and Flashback Database, give DBAs the ability to easily pinpoint and "flash back" to data in a previous state using log information. And the flash recovery area—automatically managed disk space for recovery-related data files—can allow for faster recovery than going to a backup tape and also simplifies Oracle Recovery Manager (RMAN) administration. For more information on Oracle Flashback technology, see the nextSTEPS box below, and for more information on using the flash recovery area, check out Arup Nanda's article, Recover in a Flash."
High Availability Means High Performance
While businesses still need to go to disk or tape to recover from data errors—I had to have Support restore an accidentally deleted network folder for me last week—the demands of today's 24/7 businesses have of necessity eliminated the time frame for recovery from hardware failure. Today's businesses don't stop running at 5 p.m., and they can't stop running because of a failed server.
In his feature article, "Always Available," on page 30, Alan Joch reports on Oracle customers who are using Oracle Real Application Clusters (Oracle RAC) and Oracle Data Guard on inexpensive commodity hardware—not just as insurance for high availability, but to add continuous computing power to the enterprise. Oracle RAC automatically redistributes the workload of a failed server to the remaining healthy servers, and it enables companies to scale up—to add servers to the cluster to support more users and more transactions. Oracle Data Guard provides a "standby" database, ideal for a secondary site, but companies use synchronized, data-error-free Oracle Data Guard standby databases for ad hoc queries, backups, reporting, and other activities for better performance of these activities and the transactions at the primary site.
In 1989, backup to disk was not a common solution, in part because of the high cost of this storage. Today, both disk and tape backups offer fast recovery and provide inexpensive archive solutions that can also meet compliance requirements using technologies such as Oracle RMAN and Oracle Secure Backup. And enterprise high availability that once required proprietary and expensive mainframe and minicomputers now starts with inexpensive commodity hardware, and, along with technologies such as Oracle RAC and Oracle Data Guard, provides both high availability and high performance.
Tom Haunert, Editor in Chief