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Database file types and structure
Before diving into configuration parameters, let's review database architecture from a storage perspective. Most traditional database architectures consist of three basic types of files: executable and administrative space, log file space and tablespace. These files are located on mount points that correspond to logical volumes which, in turn, correspond to disk groups within the array. The files are ultimately placed on disk groups within the array and are used to ensure that transactions are fully committed while offering the ability to recover the database to a specific transaction or time if required.
From a storage administrator's perspective, the files represent different storage needs and required parameters to ensure maximum performance of the production application. Because of past limitations on physical disk I/O and size, databases were built to scale using 2GB disks with limited I/O. Database administrators were taught to architect the database using these now-antiquated techniques. In today's environments, physical disks are virtualized a couple of times before the operating system can even view the storage. By simplifying the files into three basic buckets, a storage administrator can gain a better understanding of how to architect the underlying physical disks into disk groups for the database server. Database architecture is much more complicated than the following three file types, but this approach is based on the storage administrator's perspective.
Executable and administrative space. This space doesn't require significant consideration by the storage or system administrator. It should be protected from disk failure through mirroring, and protected from corruption by backup to a secondary disk or tape. In an Oracle/SAP environment, the mount points are typically referred to as /usr/sap/<SAPID>, /sapmnt/<SAPID> and /usr/sap/trans.
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