Adaptive Server allows you to control the placement of databases, tables, and indexes across your physical storage devices. This can improve performance by equalizing the reads and writes to disk across many devices and controllers. For example, you can:
Place a database‘s data segments on a specific device or devices, storing the database’s log on a separate physical device. This way, reads and writes to the database’s log do not interfere with data access
Spread large, heavily used tables across several devices.
Place specific tables or nonclustered indexes on specific devices. For example, you might place a table on a segment that spans several devices and its nonclustered indexes on a separate segment.
Place the text and image page chain for a table on a separate device from the table itself. The table stores a pointer to the actual data value in the separate database structure, so each access to a text or image column requires at least two I/Os.
Distribute tables evenly across partitions on separate physical disks to provide optimum parallel query performance.
For multiuser systems and multi-CPU systems that perform a lot of disk I/O, pay special attention to physical and logical device issues and the distribution of I/O across devices:
Plan balanced separation of objects across logical and physical devices.
Use enough physical devices, including disk controllers, to ensure physical bandwidth.
Use an increased number of logical devices to ensure minimal contention for internal I/O queues.
Use a number of partitions that will allow parallel scans, to meet query performance goals.
Make use of the ability of create database to perform parallel I/O on as many as six devices at a time, to gain a significant performance leap for creating multi gigabyte databases.
