[HANA] Admission control

2019/05/06 - [Database] - [HANA] 2222250 - FAQ: SAP HANA workload Management

2019/05/01 - [Database] - [HANA] Workload Management (internal)

 

 

Overview

• Load 정도를 위한 임계치 설정
  • Host CPU
  • Used memory / memory limit (GAL)
• Overload protextion behaviors
  • Queueing incomming requests
  • Rejecting incomming requests

• 예외
  • Admin-privileged session (예. SESSION_ADMIN, WORKLOAD_ADMIN 등)
  • 자원의 소비를 줄이도록 도와주는 요청 들 (예. Commit, Rolback, Disconnect 등)

 

 

적용 및 모니터링

• Configuring addmission control

구분	Parameter	Default	Detail
indexserver.ini -> [admission_control]	enable	True	turn on/off entire features
	queue_cpu_threshold	90 %	threshold to en/dequeue using CPU
	queue_memory_threshold	90 %	threshold to en/dequeue using memory
	reject_cpu_threshold	0 (disabled)	threshold to reject using CPU
	rejext+memory_threshold	0 (disabled)	threshold to reject using memory
	averaging_factor	70 %	weight in calculating load indicator
	statistics_cllection_interval	1000 ms	interval to collect load

 

• Queue management

구분	Parameter	Default	Detail
indexserver.ini -> [admission_control]	max_queue_size	10000	max number of requests to enqueue
	dequeue_interval	1000 ms	interval to dequeue
	dequeue_size	50	number of request to dequeue by once
	queue_timeout	600 sec	default timeout for enqueued requests
	queue_timeout_check_interval	10000 ms	interval to check timeout requests

 

• 모니터링
  • M_ADMISSION_CONTROL_STATISTICS
  • M_ADMISSION_CONTROL_QUEUES
  • M_ADMISSION_CONTROL_EVENTS
  • M_LOAD_HISTORY_SERVICE
  • M_CONNECTIONS.CONNECTION_STATUS
    • Connection의 요청이 enqueued 되면 status는 'QUEUEING'로 나타남
• 제약사항
  • 현재 수행중인 Request가 아닌 새로운 request에만 적용 됨
  • Session layer에서 요청을 평가함 = 내부 요청은 언제나 수행 됨
  • Rejection isn't enabled by default since it requires proper handling in client side
  • In A-A (Read only)
    • Secondary를 사용할 수 있는 상태에서 Primary에 높은 부하가 있는 경우
      secondary에서 요청이 실행되는 경우에도 request는 primary에서 대기하게 됨