parallel_max_servers

psufnxk2000發表於2013-11-05
Health Check Alert: PARALLEL_MAX_SERVERS should be greater than or equal to the minimum recommended value (Only applies to data warehousing) (Doc ID 957430.1) 在資料倉儲中, parallel_max_servers應該大於等於 最小的推薦值(4*cpu_count)
如果有並行 效能問題並且 cpu使用沒有超過90,考慮增加這個引數 ,推薦 10*cpu_count或更高



In this Document 
  Purpose 
  Scope 
  Health Check 10730: PARALLEL_MAX_SERVERS should be greater than or equal to the minimum recommended value (Only applies to data warehousing) 
     Description 
     Risk 
     Recommendation 
  References 
Applies to:


Oracle Server - Enterprise Edition - Version: 9.2 to 11.2
Information in this document applies to Any Unix,Any Microsoft Windows,.
Health Check Category: Performance
Severity Level: Warning
Purpose


This document provides a quick reference explaining the following Health Check Alert:


Scope


Before reading this article, the user should have a good understanding of Data Warehouse.
Health Check 10730: PARALLEL_MAX_SERVERS should be greater than or equal to the minimum recommended value (Only applies to data warehousing)


IMPORTANT


My Oracle Support provides a proactive health check that automatically detects and notifies you of the existence of this issue before it impacts your business. To leverage this proactive support capability, install the Oracle Configuration Manager (OCM). Information on installing the Oracle Configuration Manager can be found on the Collector tab of My Oracle Support. To view the full portfolio of health checks available, see Note 868955.1
Description


Verifies that PARALLEL_MAX_SERVERS is set to a minimum of 4*CPU_COUNT which is needed for databases that are used for data warehousing (DW) purposes. The preferred value is 10*CPU_COUNT or higher. (NOTE: It is not possible for Oracle to accurately verify whether this database instance is being used for DW purposes. If this database is not being used for these purposes, this check can be safely ignored and suppressed.)


Risk


If this database is being used for data warehousing (DW) purposes, a low value of PARALLEL_MAX_SERVERS may prevent all parallel executions from running in parallel and the available resources from being fully utilized.


Recommendation


If this database is being used for data warehousing (DW) purposes, the value of PARALLEL_MAX_SERVERS may need to be increased. If parallel execution downgrades are observed and the CPU usage is not over 90, consider increasing the value of PARALLEL_MAX_SERVERS. The minimum value should be greater than or equal to 4*CPU_COUNT. The recommended value is 10*CPU_COUNT or higher. The value of the PARALLEL_MAX_SERVERS parameter can be changed by using the alter system command (alter system set = scope=both). (NOTE: It is not possible for Oracle to accurately verify whether this database instance is being used for DW purposes. If this database is not being used for these purposes, this recommendation can be safely ignored and suppressed).


References


Document 30790.1 Init.ora Parameter "PARALLEL_MAX_SERVERS" Reference Note

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