IS RMAN REALLY WORTH THE TROUBLE
Tim Gorman, SageLogix, Inc.
Abstract
Oracle's Recovery Manager (RMAN) was first introduced with Oracle8 release 8.0 in 1997, and acceptance of the product has been slowed due to the well-deserved reputation of being difficult to install. Add this to the fact that RMAN is entering a market that is already well-served with products such as BMC SQL BackTrack, and you have even more reluctance to accept Oracle Corporation's late entry to the database backup-and-recovery market. But RMAN provides three crucial features that no other solution, whether purchased from another vendor or custom-built, can provide. And, depending on your requirements, these three features should make the difference between deciding to use RMAN or using another backup-andrecovery solution, whether it is a purchased from a vendor or custom-built. So, the decision of whether to use RMAN or not should really not hinge on the widely discussed difficulties in integrating it with media-management vendor (MMV) software. Arguably, it also shouldn't hinge on a comparison of look-and-feel and ease-of-use with the more-established products against which it competes. After all, it is a relative latecomer to the arena, and Oracle's track record has been positive in the area of improvements. Instead, this paper will explain the three crucial features: the background behind them and what problems they resolve. Then, you should be able to consider the advantages of these features and decide whether they are important to your installation, or not. If they are important, then going through the hassles of getting RMAN up and running are worth it. This paper and its associated presentation is intended to clarify your decision on whether to utilize RMAN or not, if you haven't yet made such a decision; or to validate your decision, if it has already been made. What is all the fuss about The Recovery Manager has been architected to support backup and recovery operations on all of the 80+ platforms on which Oracle runs, including the Windows platforms, all of the UNIX variants, mainframes, and a variety of other proprietary operating systems such as Compaq Open-VMS. Because of this portability requirement, Oracle designed RMAN in two halves: the generic Oracle half and the extremely specialized media-management half. The generic Oracle half of RMAN is, indeed, common across all of the platforms upon which Oracle resides. It includes: The end-user presentation layer, consisting of either the graphical user-interface (GUI) presented from the Backup Manager module of Oracle Enterprise Manager (OEM) or the command-line interface (CLI) from the server's operating system command-line. The Oracle server processes which perform the actual work of reading datafiles, control files, and both on-line and archived redo log files during a backup operation, sending the information as either backup sets or image copies to the media-management layer. These same Oracle server processes also request those backup sets or image copies from the media-management layer and write information down to datafiles, control files, and redo log files during a restore or recovery operation. The Recovery Catalog, a limited version of which is stored locally in the control files of the database being backed-up, restored, or recovered. A more extensive version of the Recovery Catalog can optionally also be created in a remote Oracle database; it is highly recommended to use this functionality in order to exploit RMAN's capabilities to their fullest. The Recovery Catalog is used to record all backup activities and structural information about the database in order to automate restore and recovery activities. The other half of Recovery Manager, the media-management layer, is either platform-specific or, in some cases, simply based on preferences in the event that there is a choice of media-management products. On

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