LSF 클러스터, 잡, 큐

00 Clusters, Jobs, and Queues

• The IBM Spectrum LSF ("Load Sharing Facility") software is industry-leading enterprise-class software that distributes work across existing heterogeneous IT resources to create a shared, scalable, and fault-tolerant infrastructure, that delivers faster, balanced, more reliable workload performance and reduces cost

• 

• First-come, first-served schedulint (FCFS)
  • LSF 스케줄링의 기본값
  • Jobs are considered for dispatch based on their order in the queue.

01 '클러스터'란 (Cluster)

1. 정의

• A group of computers (hosts) running LSF that work together as a single unit, combining computing power and sharing workload and resources.
• A cluster provides a single-system image for a network of computing resources.
• Hosts can be grouped into clusters in a number of ways. A cluster could contain:
  • All the hosts in a single administrative group
  • All the hosts on one file server or sub-network
  • Hosts that perform similar functions

2. Configuration

• Define hosts in your cluster in lsf.cluster.cluster_name file
• tip: The name of your cluster should be unique. It should not be the same as any host or queue.

 

02 '잡'이란 (Job)

1. 정의

• A unit of work runs in the LSF system.
• A job is a command that is submitted to LSF for execution.
• LSF schedules, controls, and tracks the job according to configured policies. 
• Jobs can be complex problems, simulation scenarios, extensive calculations, anything that needs compute power.

2. Job Slot

1) 정의

• A job slot is a bucket into which a single unit of work is assigned in the LSF system.
• Hosts are configured to have a number of job slots available and queues dispatch jobs to fill job slots.

2) Configuration

• Define job slot limits in lsb.resources file

3. Job States란

1)  정의: Job의 상태

2) 종류

종류	설명
PEND	Waiting in a queue for scheduling and dispatch
RUN	Dispatched to a host and running
DONE	Finished normally with zero exit value
EXIT	Finished with non-zero exit value
PSUSP	Suspended while pending
USUSP	Suspended by user
SSUSP	Suspended by the LSF system
POST_DONE	Post-processing is completed without errors
POST_ERR	Post-processing is complete with errors
WAIT	Members of a chunk job that are waiting to run

03 '큐'란 (Queue)

1. 정의

• A cluster wide container for jobs.
• All jobs wait in queues until they are scheduled and dispatched to hosts.
• Queues do not correspond to individual hosts; each queue can use all server hosts in the cluster, or a configured subset of the server hosts.
• When you submit a job to a queue, you do not need to specify an execution host. 
• LSF dispatches the job to the best available execution host in the cluster to run that job.
• Queues implement different job scheduling and control policies.

2. Configuration

• Define queues in lsb.queues
• Tip: The names of your queues should be unique. They should not be ths same as the cluster name or any host in the cluster.

04 클러스터, 잡, 큐 관련 명령어

분류	명령어	설명
Cluster	lshosts	클러스터 내의 호스트들에 관한 정적 (static) 자원 (resource) 정보 출력
	bhosts	클러스터 내의 서버 호스트들에 관한 자원 (resource)과 잡 (job) 정보 출력
	lsid	LSF 버전, 클러스터 이름, Master 호스트 이름 출력
	lsclusters	클러스터 상태와 크기 출력
Job	bjobs	시스템 내의 job들 출력
	bsub	job 제출
Job Slot	bhosts	호스트 및 호스트 그룹의 job slot limit 출력
	bqueues	큐의 job slot limit 출력
	busers	사용자 및 사용자 그룹의 job slot limit 출력
Queue	bqueues	사용 가능한 queue 출력
	bsub -q	지정된 queue에 job 제출
	bparams	default queue들 출력

참조

1. https://www.ibm.com/docs/en/spectrum-lsf/10.1.0?topic=lsf-clusters-jobs-queues 
2.