Intelligent Data Placement
Intelligent Data Placement enables you to specify disk regions on Oracle ASM disks for best performance. Using the disk region settings, you can ensure that frequently accessed data is placed on the outermost (hot) tracks which have greater speed and higher bandwidth. In addition, files with similar access patterns are located physically close, reducing latency. Intelligent Data Placement also enables the placement of primary and mirror extents into different hot or cold regions.
Intelligent Data Placement settings can be specified for a file or in disk group templates. The disk region settings can be modified after the disk group has been created. The disk region setting can improve I/O performance by placing more frequently accessed data in regions furthest from the spindle, while reducing your cost by increasing the usable space on a disk.
Intelligent Data Placement works best for the following:
Databases with data files that are accessed at different rates. A database that accesses all data files in the same way is unlikely to benefit from Intelligent Data Placement.
Disk groups that are more than 25% full. If the disk group is only 25% full, the management overhead is unlikely to be worth any benefit.
Disks that have better performance at the beginning of the media relative to the end. Because Intelligent Data Placement leverages the geometry of the disk, it is well suited to JBOD (just a bunch of disks). In contrast, a storage array with LUNs composed of concatenated volumes masks the geometry from Oracle ASM.
if the data is frequently accessed and mostly read only, put primary extents in the host region and mirror extents in the cold region. if the data is frequently accessed and updated ,put both primary and mirror extents in the hot region.” |
