CategoryRAC

Clusterware启动顺序

Cluster启动顺序大致可以解释为这样的,
INIT也就是init.ohasd (with respawn),该脚本启动了OHASD进程 (Oracle High Availability Services Daemon).  这个daemon又派生了4个重要进程.

Level 1: OHASD Spawns:

  • cssdagent – Agent responsible for spawning CSSD.
  • orarootagent – Agent responsible for managing all root owned ohasd resources.
  • oraagent – Agent responsible for managing all oracle owned ohasd resources.
  • cssdmonitor – Monitors CSSD and node health (along wth the cssdagent).

Level 2: OHASD rootagent spawns:

  • CRSD – Primary daemon responsible for managing cluster resources.
  • CTSSD – Cluster Time Synchronization Services Daemon
  • Diskmon
  • ACFS (ASM Cluster File System) Drivers

Level 2: OHASD oraagent spawns:

  • MDNSD – Used for DNS lookup
  • GIPCD – Used for inter-process and inter-node communication
  • GPNPD – Grid Plug & Play Profile Daemon
  • EVMD – Event Monitor Daemon
  • ASM – Resource for monitoring ASM instances

Level 3: CRSD spawns:

  • orarootagent – Agent responsible for managing all root owned crsd resources.
  • oraagent – Agent responsible for managing all oracle owned crsd resources.

Level 4: CRSD rootagent spawns:

  • Network resource – To monitor the public network
  • SCAN VIP(s) – Single Client Access Name Virtual IPs
  • Node VIPs – One per node
  • ACFS Registery – For mounting ASM Cluster File System
  • GNS VIP (optional) – VIP for GNS

Level 4: CRSD oraagent spawns:

  • ASM Resouce – ASM Instance(s) resource
  • Diskgroup – Used for managing/monitoring ASM diskgroups.
  • DB Resource – Used for monitoring and managing the DB and instances
  • SCAN Listener – Listener for single client access name, listening on SCAN VIP
  • Listener – Node listener listening on the Node VIP
  • Services – Used for monitoring and managing services
  • ONS – Oracle Notification Service
  • eONS – Enhanced Oracle Notification Service
  • GSD – For 9i backward compatibility
  • GNS (optional) – Grid Naming Service – Performs name resolution

11.2_clusterware

数据仓库海量数据表拆分和并行

数据仓库海量数据表拆分和并行
表拆分
1.数据仓库海量数据计算解决思路:表拆分
起因:单个表数据量太大,计算时间太长,需要优化

2.表拆分的实际应用思路:
按照某列,做HASH计算,得到一个整数
oracle提供了包dbms_utility
function get_hash_value(name varchar2, base number, hash_size number)
return number
根据键值把数据插入到不同的表,分别计算,然后再汇总。
或者自己定义拆分的计算函数,例如,利用mod函数,利用数字列的尾号等等,只要能把数据均匀分开即可。

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如何控制RAC跨节点并行计算

RAC的一大优点就是可以跨节点进行并行计算,那么如何控制并行运算?这就是这篇文章要讨论的内容。

合理设置跨节点并行,需要先设置一些参数:
instance_groups:这个参数主要是设置该节点实例是否属于某一个实例组。每个节点可以设置多个不同的实例组名,实例组名用逗号隔开。
parallel_instance_group设置的值为instance_groups里面设置的值,表明这个节点上面进行的并行操作可以跨越哪些实例组。
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