1. AliEn uses bbFTP for the file transfers. Every FTD runs a server, and all the others FTD can connect and authenticate to it using certificates. bbFTP implements its own transfer protocol which is optimized for large files (larger than 2GB). Its main features are: SSH and Certificate authentication modules Big windows as defined in RFC1323 Multi-stream transfer On-the-fly data compression Automatic retry Customizable time-outs Transfer simulation RFIO interface AliEn Resource Brokers AliEn Services AliEn has been implemented having the idea of ‘web services’ in mind. Most of the services are built using SOAP (Simple Object Access Protocol), which allows easy communication among processes in a distributed environment. AliEn (ALICE Environment) is a lightweight GRID framework developed by the Alice Collaboration. When the experiment starts running, it will collect data at at a rate of 2 PB per year, producing more than 10 9 files per year. All these files, including all simulated events generated during the preparation phase of the experiment, must be accounted and reliably tracked in the GRID environment. The backbone of AliEn is a distributed file catalogue, which associates universal logical file name to physical file names for each dataset and provides transparent access to datasets independently of physical location. The file replication and transport is carried out under the control of the File Transport Broker. In addition, the file catalogue maintains information about every job running in the system. The jobs are distributed by the Job Resource Broker that is implemented using a simplified pull (as opposed to traditional push) architecture. This poster describes the Job and File Transport Resource Brokers and shows that a similar architecture can be applied to solve both problems. Predrag Buncic, Andreas Peters, Pablo Saiz for the ALICE Collaboration ClassAds Classified Advertisements (classads) are the lingua franca of Condor. They are used for describing jobs, workstations, and other resources. Classads are exchanged by Condor processes to schedule jobs. AliEn uses classads for the definition of jobs, machines and file transfers. Two examples of classads are shown below. FOR MORE INFORMATION: http://alien.cern.ch IS Proxy Logger Authen CPUServer Only one per organization Cluster Monitor Cluster Monitor CE Process Monitor Process Monitor SE FTD At least one per site Broker TransServer TBroker Optimizer Toptimizer Job status A job in AliEn goes through the stages shown in the diagram. First WAITING; then a CE picks it up and it is ASSIGNED; QUEUED when it is submitted to the local batch system; RUNNING when the job starts to execute on the worker node, and finally DONE when it finishes AliEn also provides a method to validate jobs. If a job has to be validated, a new process for the validation will start when the job finishes. Then, the status of the job will be VALIDATED if it passes the validation procedure, otherwise, it will be marked as FAILED Broker Yes: Select Match ? No: Next Resource (CE or FTD) Tasks (Jobs or Transfers) Requirements = ( other.Type == "machine" )&&(member(other.Packages,"AliRoot") ); Packages = "AliRoot"; Arguments = "--round 2002-02 --run 071 --event 269 --version v3.08.02 -–grun G+F"; Executable = "/Alice/bin/AliRoot.sh"; InputFile = {LF:/alice/simulation/2002-02/v3.08.02/00071/Config.C", "LF:/alice/simulation/2002-02/v3.08.02/00071/grun.C"}; Type = "Job"; Broker FTD SE … DB SE Optimizer SE Server New transfer requested Castor, HPSS, HIS, Tape,adsm, File Disk… AliEn Computing model The AliEn Computing model is made of a central server, which keeps track of all the jobs that have to be executed in the system. Each site has at least one ClusterMonitor. This service will ask the Broker for jobs to execute (taking into account the specifications of the site, like packages installed or close storage elements), and will send them to the Computing Elements. They will send them to batch queues (like LSF or PBS), and register the output in the system. There is as well an optimizer, that checks the jobs waiting to be executed. The optimizer is in charge of modifying the waiting jobs. For example, replicating the data that some jobs require in sites with more computer power. AliEn Transfer model The main component of the transfer model is, like in the case of the computing model, a database with all the transfers that have to be done. A server inserts new entries in the database, and an optimizer checks the entries and sets the priorities for the transfers. Each site runs a FTD (File Transfer Daemon). Each FTD contacts the Broker every minute and requests transfers. Brokers The AliEn Brokers have a list with all the classads of the tasks that have to be done, and a priority for each task. Whenever a new resource is free, it will send its classads to the corresponding broker, The Broker will do the matching with the highest priority task that matches all the requirements. If no Requirements = ( other.Type == "Job" ); Packages = { "ROOT::3.03.07", "ROOT", "AliRoot::3.08.Rev.03", "AliRoot", "AliRoot::3.08.Rev.04" }; CloseSE = { "Alice::CERN::Castor", "Alice::CERN::File", "Alice::CERN::scratch", "Alice::CERN::pcepaip19" }; CE = "Alice::CERN::LXSHARE"; Host = "lxplus051.cern.ch”; GridPartitions={ “Production”}; tasks are found, the resource will wait for a while and request a new task Broker Cluster Monitor Cluster Monitor Cluster Monitor CE … DB CE Optimizer CE OTHER VIRTUAL ORGANISATIONS OR GRID IMPLEMENTAIONS Server New Job Submitted LSF,PBS,CONDOR,… The transfers have to be made in several steps: first, the source FTD has to bring a copy from the local mass storage system into a scratch directory (this step is not necessary if bbFTP can access the storage directly); then the remote FTD can fetch the file and put it into its own storage; finally, the source FTD deletes the scratch copy of the file. ******************************************* * * W E L C O M E to R O O T * * * Version 3.03/09 3 December 2002 * * * You are welcome to visit our Web site * * http://root.cern.ch * * ******************************************* Compiled for linux with thread support. CINT/ROOT C/C++ Interpreter version 5.15.61, Oct 6 2002 Type ? for help. Commands must be C++ statements. Enclose multiple statements between { }. root [0]newanalysis->Submit(); Analysis Macro MSS CE merged Trees + Histograms ? Query for Input Data Job splitting AliEn also offers the possibility of splitting jobs that require data spread over several sites. Each site will compute their local available data, and then the output of all the jobs will be merged, giving back the output as if it had run in only one place. The user should not care at all where the job is executed. GP CALMA