Expert Oracle Exadata - Parent Directory

CHAPTER 7 RESOURCE MANAGEMENTI/O Resource PlanI/O Resource DirectivesDatabaseLevel 1 I/OAllocationSCRATCH 60%SNIFFOTHERLevel 2 I/OAllocation80%Level 3 I/OAllocation100%Figure 7-9. Interdatabase IORM planIn Figure 7-9, our SCRATCH database, the highest-priority database, is guaranteed 60% of the total I/O onlevel 1. On level 2, our SNIFF database takes its 80% slice of the remaining 40% of unallocated I/O fromlevel 1. Any unused I/O from level 1 also cascades down to level 2. In addition to any unconsumed I/Ofrom levels 1 and 2, databases on level 3 will equally share the unallocated 16% of total I/O, (16% = 80% ×20%). Note that any databases that do not explicitly appear in the active I/O resource plan willautomatically be assigned to the OTHER group.Configuring Interdatabase IORMInterdatabase I/O Resource Manager is configured using an IORM plan. This plan determines thedatabase I/O priorities for the storage cell. IORM plans are created using the CellCLI command ALTERIORMPLAN. There can be only one IORM plan per storage cell, regardless of how many ASM instances(clustered or single instance) use it for storage. Creating an Interdatabase IORM plan is fairly simple. Thefirst step is to determine what your allocation policy should be for each database. You will use theseallocation policies to define the directives for your IORM plan. The LEVEL attribute specifies the priority adatabase should be given relative to other databases in the plan. The ALLOCATION attribute determinesthe percentage of I/O a database will be given out of the total I/O available on its level. The followingexample demonstrates how you to create an IORM plan to implement the allocation policies illustratedin Figure 7-9.CellCLI> ALTER IORMPLAN -dbPlan=( -(name=SCRATCH, level=1, allocation=60), -(name=SNIFF, level=2, allocation=80), -(name=other, level=3, allocation=100))IORMPLAN successfully alteredThe CellCLI command list iormplan detail displays our new IORM plan. Notice that the catPlanattribute is empty. This is a placeholder for the Category IORM plan we’ll be looking in the next topic.CellCLI> list iormplan detailname:catPlan:dbPlan:status:enkcel01_IORMPLANname=SCRATCH,level=1,allocation=60name=SNIFF,level=2,allocation=80name=other,level=3,allocation=100inactive210