oracle RAC DRM基本概念 |
發(fā)布時間: 2012/9/15 18:06:10 |
在oracle RAC中,每個實例均存在一個數(shù)據(jù)緩存池,每個block的改變都將實例間進行資源協(xié)調(diào)以獲取最大化性能,從而保證數(shù)據(jù)的完整性。 在RAC集群中,每個被緩存的數(shù)據(jù)copy,也叫做緩存資源,均存在一個叫做master節(jié)點的實例。 在10.1.0.2中,一旦一個cache resource被master一個實例節(jié)點, 對緩存資源的重新remaster或者說master節(jié)點的自動改變僅僅會發(fā)生在RAC實例節(jié)點的正常啟;蛘呒汗芾碣Y源間的非正常問題發(fā)生。 也就是說,如果NODE B是一個緩存資源的master節(jié)點,這個資源將被一直master到NODE B直到發(fā)生RAC節(jié)點的重新配置操作。 在oracle 10g中引進一個新的資源remaster概念叫做DRM(Dynamic Resource management [ID 390483.1]),通過DRM,RAC實例節(jié)點的重新配置 已經(jīng)不再是cache資源被重新remaster的因素,如果cache resource被節(jié)點A頻繁訪問,一個資源可以從NODE B remaster到NODE A。 其他的一些概念如下: In 10gR1 DRM is driven by affinity of files and in 10gR2 it is based on objects. DRM attributes are intentionally undocumented since they may change depending on the version. These attributes should not be changed without discussing with Support. Two instance will not start a DRM operation at the same time however lmd,lms,lmon processes from all instances collectively take part in the DRM operation. Normal activity on the database is not affected due to DRM. This means users continue insert/update/delete operations without any interruptions. Also DRM operations complete very quickly. DRM many cause" latch: cache buffers chains" and "latch: object queue header operation " wait event, you can go throught this way to disable DRM: _gc_affinity_time=0 _gc_undo_affinity=FALSE also, you can used another two implicit parameters dynamic change _gc_affinity_limit=10000000 本文出自:億恩科技【mszdt.com】 服務(wù)器租用/服務(wù)器托管中國五強!虛擬主機域名注冊頂級提供商!15年品質(zhì)保障!--億恩科技[ENKJ.COM] |