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Exadata I/O Resource Manager (Exadata IORM)

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Exadata I/O Resource Manager (Exadata IORM)

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Exadata I/O Resource Manager (Exadata IORM)

  1. 1. I/O Resource for Exadata Databases ---------------------------------------------------------There are three plans - category, interdatabase, and intradatabase which are used together by Exadata to allocate I/O resources. Intradatabase Resource Plan: To create an intradatabase resource plan Database resource management is configured within each database, using Database Resource Manager. This is the only IORM feature that is needed If only one database is using Exadata. Interdatabase Resource Plan: this plan specifies how resources are allocated among multiple databases for each cell. Category Resource Plan : Exadata is hosting multiple databases and to allocate resources primarily by the category of the work being done. IORM plan : Both the interdatabase plan and the category plan which are defined in a cell object known as the IORM plan. I/O Resource Management Plan explained : i. First the category plan is used to allocate resources among the categories. ii. After selected a category, the interdatabase plan is used to select a database. The selected databases must have consumer groups with the selected category. iii. Finally, the selected database’s intradatabase plan is used to select one of its consumer groups. The percentage of resource allocation represents the probability of making a selection at each level which is measured by below formula: Pcgn = cgn / sum(catcgs) * db% * cat% where: • Pcgn is the probability of selecting consumer group n. • cgn is the resource allocation for consumer group n. • sum(catcgs) is the sum of the resource allocations for all consumer groups in the same category as consumer group n and on the same database as consumer group n. • db% is the database allocation percentage in the interdatabase plan. • cat% is the category allocation percentage in the category plan.
  2. 2. Consumer Group (CG) names are abbreviated to CG1, CG2, and so on. IORM is concerned with the ratio of consumer group allocations within each category and database. IORM allocation for Database A on Batch Category -----------------------------------------------------------------CG1: (15/(15+10)*70%*40%)= 16.8%; CG2: (10/(15+10)*70%*40%)= 11.2%; IORM allocation for Database A on Interactive Category ------------------------------------------------------------------------CG3: (35/(35+40)*70%*60%)= 19.6%; CG4: (40/(35+40)*70%*60%)= 22.4%; IORM allocation for Database B on Batch Category -----------------------------------------------------------------CG5: (22/(22+18)*30%*40%)= 6.6%; CG6: (18/(22+18)*30%*40%)= 5.4%; IORM allocation for Database B on Interactive Category ------------------------------------------------------------------------CG7: (15/(15+45)*30%*60%)= 4.5%; CG8: (45/(15+45)*30%*60%)= 13.5%;
  3. 3. IORM is related with the ratio of consumer group allocations within each category and database. Findings: i. The value of Consumer Groups receives same of I/O resources from IORM if the intradatabase plan allocations are doubled. For example if we doubled for CG1 to 30% and CG2 to 20% respectively. CG1: (30/(30+20)*70%*40%)= 16.8%; CG2: (20/(30+20)*70%*40%)= 11.2%; This is because the allocation to CG1 remains 50% greater than the allocation to CG2. ii. Again for the ratio of consumer group allocations within each category and database similar allocation through IORM. Ex: Between CG1 and CG3 and between CG6 and CG8 For database A -------------------CG3 belongs to the higher priority category (60%) than CG1 ( 40%) CG3 much larger intradatabase plan allocation (35% versus 15%). For database B ------------------CG8 belongs to the higher priority category (60%) than CG6 ( 40%) CG8 much larger intradatabase plan allocation (45% versus 18%). Exadata cells use the IORM plan in conjunction with the DBRM plans propagated by the databases to allocate I/O resources.

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