A Computing Tier 2 Node Eric Fede – LAPP/IN2P3

2 Eric Fede – 1st Chinese-French Workshop Plan What is a Tier 2 –Context and definition To be a Tier 2 –Objectives and commitments Building a Tier 2 –Tier 2 specifications –Infrastructures –Team Daily works on Tier 2 Conclusion

3 Eric Fede – 1st Chinese-French Workshop What is a Tier 2 Context –To provide computing and storage needed to process and analyse the data gathered by LHC, the Worldwide LHC Grid Computing project was defined. –WLCG define 4 type of computing resource : Tier 0, Tier 1, Tier 2 and Tier 3 Tier 2 definition (usual version) –Centres consisting of one or several collaborating computing facilities, which can store sufficient data and provide adequate computing power for end-user analysis tasks and Monte Carlo simulation. –Share between analysis and simulation depend of the application.  Only simulation for LHCb  Both for ATLAS and CMS

4 Eric Fede – 1st Chinese-French Workshop What is a Tier 2 Tier-1 Data acquisition Tier-2

5 Eric Fede – 1st Chinese-French Workshop How to be a Tier2 ?

6 Eric Fede – 1st Chinese-French Workshop To be a Tier 2 Tiers 2 have to declare to be agree with a Memorandum Of Understanding who define roles, objectives and commitment of Tiers 2. – Provisioning –Provisioning a managed disk storage  Providing permanent data storage for files and database.  Providing temporary data storage for files and database.  This storage should be “grid enable” according to standards –Provisioning a access to the stored data by other centre of the grid  Any Tier 2 may have access data to any Tier 1  In particular, the network bandwidth and services for data exchange with associate Tier 1 should be ensure.

7 Eric Fede – 1st Chinese-French Workshop To be a Tier 2 –Provisioning a processing capacity  Should be access by the grid standards –Provisioning some services according to the experiment requirements  Sharing grid services (resource broker,…..)  Dedicated to experiences ( files catalogue, VOBox,…)  … Level of availability –Average availability measured on annual basis need to be upper at 95 % ( 18 days per year of unavailability) –Responding delay to operational problems : from 2 hours to 72 depending of the services affected and the periods where the problem occur. Tier’s 2 have a real long term role of services provider

8 Eric Fede – 1st Chinese-French Workshop Building a Tier 2

9 Eric Fede – 1st Chinese-French Workshop Building a Tier 2 Tier 2 workspace The site has to ask himself some questions about her Tier 2 to define which Tier 2 it want being. –Which applications will be accepted on the T2 ?  Could influenced the Tier capacity and organisation For the LCG experiences : from 1 to 4. Majority of Tier 2 supported one or more none LHC VO. –To be or not be a 100% grid site ?  Share resources between grid users and non grid users Some sites need to provide some computing resources out of grid aspects. oA part of the resources (storage, computing) can be acceded by a none grid process

10 Eric Fede – 1st Chinese-French Workshop Building a Tier 2 –What are the constraints of my site ?  In terms of infrastructure.  In terms of manpower.  Both aspects are for a part linked to the next point. –The budget aspect  The financing of the Tier is perennial or not ?  Useful to anticipate the infrastructure and resources evolution.

11 Eric Fede – 1st Chinese-French Workshop Building a Tier 2 –What type of tier we want ?  A site = a Tier 2 This is the first view that we have about a tier2.  A set of sites = one Tier 2 On this view a Tier 2 is a federation of site. Must establish unified technical and operational management.  Today 50 % of the Tiers 2 are a federation of sites ( from 2 to 8 geographical sites ) Italy Tiers 2 are dedicated site. UK Tiers 2 are all a federation of site. France, both approach are done. –… On black, information extracted from a survey of T2s done this summer (25 answers)

12 Eric Fede – 1st Chinese-French Workshop Building a Tier 2 Infrastructure requested (hardware) –Networking  A fast network connection to national research an education networks ( in order to be connected to the associate Tier 1).  Today, all the Tier 2 ( which have participates to the survey) have at less 1Gb/s.  A fast network core to interconnect the Tier 2 elements/services. This task can spend many time because the number of partner involved on network infrastructure can be large. On black, information extracted from a survey of T2s done this summer (25 answers)

13 Eric Fede – 1st Chinese-French Workshop Building a Tier 2 Infrastructure requested (hardware) –Computing  A significant computing power.  No rules exist about the lower limit to be a Tier 2, but : ∑ Tier 2 = ∑ Tier 1  Today the Tier2 which support only one VO provide (or will provide) more than 400 cpu and more than 800 cpu for the Tier 2 which support 4 VO. Wait the last period for buying the computing can give the feeling that we have more performances for less cpu, but growing resources too fast is not easy. On black, information extracted from a survey of T2s done this summer (25 answers)

14 Eric Fede – 1st Chinese-French Workshop Building a Tier 2 Infrastructure requested (hardware) –Storage  Tier 2 will provide only disk storage, no MSS.  The size of the storage is from 50 TB to 800 TB.  Not really proportional to the number of VO. –Computing room infrastructure  Probably the most important infrastructure element, because other ( computing, storage,…) are dependent on her.  Space on computer rooms.  Cooling.  Electric power. The principal reason of downtime during the last year on LCG sites is related to a cooling or power problem.

15 Eric Fede – 1st Chinese-French Workshop Building a Tier 2 Infrastructure requested (hardware) Concerning the hardware infrastructure, the word to keep on mind is ANTICIPATE  Power, cooling requirements  Computing, storage provisioning  Time to obtain an adequate network link

16 Eric Fede – 1st Chinese-French Workshop Building a Tier 2 Infrastructure requested (services) –Deployment and configuration of  Operating system.  Grid middleware.  Maybe application software.  Not trivial because size of resources ( x hundred of cpu and disk) grid services complexity grid services dependency. a coherent system is essentiel  Needs expertises.  The usage of some tools can be useful. Yaim, Quattor,…..

17 Eric Fede – 1st Chinese-French Workshop Building a Tier 2 –Storage services  Management of the local storage solution (SAN, NAS, Castor,…).  Management of the sharing file system. Use by workers to “mount” some storage area (application software, working directory,…) Many candidate (GPFS, Luste, AFS,…)  Management of the grid storage service (DPM, dcache,…). Keeping the namespace coherent with the data  Management of the channels for access to storage. Finding the good parameter to optimize the transfer ( # stream) –Computing services  The job manager choice (PBS, LSF,Torque, BQS,…).  Definition of the scheduler rules. The efficiency of the site (computing point of view) depend of this.  Job parallel compatibility (MPI deployment)

18 Eric Fede – 1st Chinese-French Workshop Building a Tier 2 –Monitoring services  The control and the management of the Tier 2 require having a global view of the resource. Services overloaded (RB), scheduling efficiency, storage availability,..  Required to define what are the interesting parameters to supervise  Important in order to “solve” the problems before they comes and consequently increase the Tier 2 availability. –Control services  Mainly the control of the hardware resources (IPMI controller) Shutting down properly resources in case of power failure. Starting properly resources when the power come back. ….

19 Eric Fede – 1st Chinese-French Workshop Building a Tier 2 Team –The main activities of the people involved on the Tier 2 are operational activities.  Involved on the deployment (hardware and software).  Services maintenance and migration.  Support for local user (not really requested by the Tier 2 activity, but in practice you have to do a part of the users support). –A part of the teams are also involved on the relations and coordination with other LCG partner and sites. –Majority of the Tier 2 have between 4 and 6 FTE (Full Time Equivalent). But change strongly from site to site. Expertise of people involved on the teams is crucial to the good Tier 2 life.

20 Eric Fede – 1st Chinese-French Workshop Daily works This is the work of every computing centre Management of resources –Optimize the resources usage.  By a tuning of the services and resources. –Evolution and migration of the resources.  New hardware, new services. Security actions – Follow the WLCG security recommendations and actions. Operation actions –Coordination with the associate Tier 1 and with others WLCG Tiers. –Follow the grid software news, because WLCG services are alive. Some of them can die, some new will have to be deployed. –…..

21 Eric Fede – 1st Chinese-French Workshop Conclusion A Tier 2 is : –A commitment on WLCG project. –An hardware infrastructure. –Providing and managing services. –A daily work to keep the system up and running. –Teams and technical competencies. Keep on mind that a Tier 2 on the next years will be what was a Tier 1 today.

22 Eric Fede – 1st Chinese-French Workshop THANK YOU QUESTIONS ?