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Database RAID Array Planning

A database RAID array (redundant array of independent drives) can provide large amounts of I/O throughput and capacity, while appearing to the operating system and RDBMS as a single large disk (or multiple disks, as desired, for manageability). The use of RAIDs can greatly simplify the database layout process by providing an abstraction layer above the physical disks, while promoting high performance.

Performance of the RAID feature provided by the operating system may not be satisfactory. To obtain the best RAID performance, use the RAID support provided by your RAID vendor.

If a RAID Array Is Not Used

If a RAID device is not in use, even if space is at a premium, you must separate indexes with names ending in _P1 from the tables on which they are created. These tables are heavily used in joins.

If you will make frequent use of Siebel Enterprise Integration Manager (EIM), you may want to put the EIM tables and indexes (names starting with EIM_) on different devices from the Siebel base tables. Both tables are accessed simultaneously during EIM operations.

Microsoft SQL Server RAID Array Planning

Table 9 describes a sample disk layout for a server dedicated to Microsoft SQL Server, where the database uses a single filegroup residing on a disk array. The use of a single RAID array for the database devices provides satisfactory performance in many cases without the administrative overhead of using individual filegroups.

Table 9. Microsoft SQL Server Recommended Disk Layout

Single mirrored

Windows OS


Single disk

Windows pagefile

Segregate for maximum performance.

Single mirrored

SQL Server logfile

Segregate sequential I/O for database performance.

3 to 5 disks (minimum) in a RAID configuration

Siebel Database data and indexes

Add as many spindles as required for performance and storage capacity.

If your enterprise requires the highest performance standards, you should place heavily used tables and their corresponding indexes, such as those listed under Sizing the Database for a Siebel Deployment, in a specific SQL Server filegroup within your database. By creating a filegroup on a specific disk or on multiple disks, you can control where tables and indexes in your database are physically located. For details, see Database Physical Device Planning.

When separating database objects into filegroups, you can avoid complex calculations by using Microsoft's recommended RAID disk layouts.

Your choice to use RAID devices or multiple filegroups to distribute database objects depends solely on how great your performance needs are. It is recommended that you work with your hardware vendor to determine the optimal RAID configuration for your specific requirements.

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