一、RAC的AWR縱覽
二、GCS等待事件
三、Global Cache Load Profile
1.可以大概估算下所用帶寬(沒有算GCS/GES Message的大小)
(received+send)*db_block_size= 901 * 8k= 7.04MB/s= 56.32Mb/s
注意這僅僅是粗略估算,一般建議private network選用10Gb帶寬
2.一條GCS/GES Message大約200 bytes
3.Estd Interconnect traffic(KB)參數計算公式
Estd Interconnect traffic (KB) = (('gc cr blocks received'+ 'gc current blocks received' + 'gc cr blocks served'+ 'gc current blocks served') * Block size) + (('gcs messages sent' + 'ges messages sent' + 'gcs msgs received'+ 'gcs msgs received')*200)/1024/Elapsed Time
4.評估的發送流量(MB) = (((GES_SENT+GCS_SENT)*200) + ((CR_SENT+CURRENT_SENT)* BLOCK_SIZE)) * 1.2 * 8 /1048576
四、Global Cache Efficiency Percentages
1.對RAC而言response time響應時間的要求比單節點更高,所以別指望用爛硬件搭出來的RAC性能比單機好!
2.如果Interconnect的網絡延遲 > IO子系統的延遲,那麼RAC本身就是性能瓶頸
3.但是IO響應時間對RAC也非常重要,例如上一講中所述log file sync=> gc buffer busy,所以千萬別用garbage storage去搭RAC!!
4.Avg global cache cr block receive time (ms):0.7
Avg global cache current block receive time (ms):1.0
1)關重要的2個指標,結合其他節點的AWR報告一起分析這2個指標,一般要求小於2ms。
2)若在RAC實例之間這2個指標差異很大,一般說明interconnect問題出現於OS buffer層或者網卡上.
5.
Time to process CR block request in the cache = (build time + flush time + send time)
Time to process current block request in the cache= (pin time + flush time + send time)
五、Messaging Statistics
1.Avg message sent queue time 一條信息進入隊列到發送它的時間
2.Avg message sent queue time on ksxp 對端收到該信息並返回ACK的時間,這個指標很重要,直接反應了網絡延遲,一般小於1ms
3.Send message有2種方式:
kjccsmg() – send message (FG direct send)
kjccqmg() – queue message (indirect send by LMS)
4.% of indirect sent messages 間接發送信息一般是排序或大的信息,流控制也可能引起indirect sent message
% of flow controlled messages 流控制最常見的原因是網絡狀況不佳, % of flow controlled messages應當小於1%
最好是% of direct sent messages所佔用比例高。
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