A. Amorim 1 The HERA-B database services detector configuration, calibration, alignment, slow control, data classification The HERA-B detector The database problem The Architecture The Berkeley-DB DBMS The client/server integration The domains and solutions Conclusions and Outlook A. Amorim, Vasco Amaral, Umberto Marconi, Tome Pessegueiro, Stefan Steinbeck, Antonio Tome, Vicenzo Vagnoni and Helmut Wolters

A. Amorim 2 HERA-B Experiment B/B-tagging B 0 /B 0 J/  K S Vertex Detector Si strip 12  m resolution RICH (  /K) multianode PMT TRD (e  h) straw tubes +thin fibers ECAL(  +e  h) W/Pb scintillator shashlik MUON (  h) tube,pad and gas pixel chambers Tracking: - ITR(<20cm): MSGC-GEM - OTR(>20cm): 5+10mm drift cells Magnet: 2 Tm C 4 F 10 HiPt trigger pad/gas pixel

A. Amorim 3 The main challenge: Selecting

A. Amorim 4 HERA-B DAQ L2-farm: 240 PC’s L4-farm 200 PC’s 1000 SHARC (DSP) Detector Front End Electronics FCS DSP SWITCH Event Control Trigger PC Trigger PC Trigger PC INTERNET SWITCH 4LT PC 4LT PC Logger PC SLT/TLT 4LT

A. Amorim 5 The HERA-B database problem To provide persistence services (including online-offline replication) to: Detector configuration Common accepted schema Calibration and alignment Distributing information to the reconstruction and trigger farms Associate each event with the corresponding database information Slow control Manage updates without data redundancy Data set and event classification Online Bookkeeping Detector Configuration Calibration and Alignment Slow Control Data Set and Event Classification Online Bookkeeping

A. Amorim 6 Characterizing the context

A. Amorim 7 Keys, objects and client/server client/server at the SDB level + RPM -> an UDP based communication package. /PM/ Descrip. field1 ; field 2; Db: /RICH/HV/ versions Key= name+ version Machine independent blub of DATA

A. Amorim 8 The Berkeley DB See Embedded transactional store with: logging, locking, commit and roll back, disaster recovery. Intended for: high-concurrency read-write workloads, transactions and recoverability. Cursors to speed access from many clients.. Open Source policy The license is free for non-commercial purposes - rather nice support No client/server support is provided

A. Amorim 9 Slow Control Interface Metadata Object Data ObjectUpdate time Pmt1000 Pmt1003 Pmt2000 Update Optimized Queries

A. Amorim 10 Associations to Events Index Objects (referenced by events) Client/server Active server interface Index Obj.... Index Obj.... Revision 0 - online Index Obj. Calibrating 1 - offline Dynamic Associations Index Obj. Created in active Servers

A. Amorim 11 Basic n-n associations (LEDA) LEDA - Object Manager (hash table implemented associations) Key objects (referenced by events) Client/server Active server interface Key key’ Key key’ Associations are navigated with iterators Using hash tables. Keys as OID’s with the scope of classes. Explicitly loaded or saved (as containers)

A. Amorim 12 GUI for editing and drawing From R&D: JAVA, TCL/TK, gtk Reusing and extending widget. Data hidden from TCL/TK ROOT database Binding Socket: Client/ Server

A. Amorim 13 General Architecture 10 9 Evt./y

A. Amorim 14 Conclusions ONLINE: Large number of Clients => Gigabytes per Update broadcast simultaneously to SLT tree of cache database servers to the 4LT Correlates (dynamically) each event with the databases objects 600 k SLC parameters using data and update objects parameter history is re-clustered on the database servers The online database system has been successfully commissioned OFFLINE: Replication mechanism decouples online from offline also provides incremental backup of the data TCP/IP gateways and proxies “data warehousing” for data-set classification -> MySQL Relation to event tag under evaluation Also providing persistency to ROOT objects Using Open Source external packages has been extremely useful.