The PVSS Oracle Archiver FW WG 6 th July 2006

Credits Many people involved IT/DES: Eric Grancher, Nilo Segura, Chris Lambert IT/PSS: Luca Canali ALICE: Svetozar Kapusta Oracle: Lothar Flatz IT/CO: Laura Fernandez, Milosz Hulboj, Piotr Golonka, Wayne Salter, Manuel Gonzalez Infrastructure LHCb, ALICE and lxshare machines for PVSS IT/PSS Oracle DB server

… EM DM RDB Driver PVSS System 1 … Val Arch 1 Val Arch m UI EM DM Driver PVSS System n Val Arch 1 Val Arch m … UI CTRL DB Server(s) RDB CTRL

CERN Requirements 150 PVSS clients Data values Insertion: values/s Queries: 5 dpes in 10 systems -> response in less than 5 secs Alarms Insertion: Avalanche: all data in one system (~10000 dpes) Regular: ~1000 dpes coming from several systems Queries Display of current alarms in AES acceptable for an operator No data loss Buffer to disk if DB not reachable

Initial version Client could insert ~100 values/sec Single value insertion Very slow client start up Very poor performance in DB server Issues with CERN environment Access rights in DB server Network performance

Client side: events insertion Assumptions Data generated with sim drivers at continuous rate One RDB manager per PVSS system Improvements achieved Current performance Data insertion: ~2000 val/s Windows, ~3000 val/s Linux Improved start up time Changes Bulk insert (moved to OCCI) Start up queries Open issues OCCI bug with memory allocation Start up dependent on history length Deadlock when many clients change archive configuration at the same time

EMDMRDB Sim X changes/s Sim Y changes/s … X + Y -Changes per block -Blocks in memory X + Y B1 blocks/s PVSS Project 1 PVSS Project 150 B150 blocks/s … DB

Client side: events query Assumptions Nearly all of the queries are dpGetPeriod, other queries not optimized Improvements tested (not sent yet to ETM) Difficult to measure Modified query to look only in data for the correspondent PVSS client Open issues Performance degradates when asking for values outside of the time interval (count > 0). This is used in the Trending tool. Possible to specify count = 0 Queries for data in remote systems go via the remote EM- DM-RDB chain Load on remote system Data not available if system not running (e.g. maintenance)

dpGetPeriod t1 t2 Count = 2 Count = 0

Client side: alarms insertion Tests Bulk insertion as for events Very poor performance Cannot handle 200 threshold crosses per sec Confirmed by ETM

DB side Assumptions One DB server per distributed system One user/schema in the DB server per distributed system Improvements (not yet officially accepted by ETM) Current performance Single Oracle server ~ val/s Scales linearly in a cluster (RAC technology) 150 clients with 500 changes/s run for one day 6 RAC nodes Low CPU usage (<40%) and low disk i/o Changes Direct path, partitioning, statistics gathering, etc Issues Space used in DB: data, index, logs, etc Allocation of new space blocks system: being followed up with Oracle Set up requires DBA rights

Buffering to disk ETM’s concept document ASCII file per block with prepared sql statements for insertion Load to DB manually triggered CERN request Use same path as for normal insertion or ASCII file with only data (e.g. CSV, tab) Import to DB with SQL loader

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