the dcs databases

The DCS Databases

Peter Chochula

31/05/2005 Peter Chochula

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Outline

• PVSS basics (boring topic but useful if one wants to understand the DCS data flow)

• Configuration Database

• DCS Archive– Architecture– Access to the DCS archive

• Current status


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Driver Layer

Communication and Storage Layer

Application Layer

UI Layer

The PVSS Architecture

User InterfaceManager

DataManager

Driver DriverDriver



EventManager

APIManager

ControlManager


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DataManager

Driver DriverDriver



EventManager

APIManager

ControlManager

In a scattered system, the managers can run on dedicated machines

In a simple system all managers run on the same machine


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DistributionManager

DistributionManager

DistributionManager


DataManager

Driver DriverDriver



EventManager

APIManager

ControlManager


DataManager

Driver DriverDriver



EventManager

APIManager

ControlManager


DataManager

Driver DriverDriver



EventManager

APIManager

ControlManager

In a distrubuted system several PVSSII systems (simple or scatered) are interconnected


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Remarks

• The DCS configuration is not static and will change in time– The managers may be scattered if needed– Individual systems may be split into distributed

system, or joined together– Devices might be added/removed, channel

assignment might change

• At present time we expect the global DCS will be formed by a distributed PVSS system consisting of individual scattered systems


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PVSSII basics - Datapoints

• PVSS data is stored as Datapoints (DP) of a given Datapoint Type (DPT)

• DPT represents data structure of the device– User definable

• DP contains information related to an instance of a device (similar to Objects and Classes)– DP can contain many read/write parameters called Datapoint

Elements (DPE)– Possible DPE types include char,integer, float, boolean … and

arrays made of them– DP contains configs, which are defining its behavior (e.g.

archiving, smoothing, alarm handling etc.)– Several status bit indicate the quality of acquired data, etc.


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Example Datapoint

DPT

DP

DPE

SystemName:DPName:DPEValue

TimestampConfig

System1:TestFloat1:floatvalue


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Remarks

• The full Datapoint name includes the system name. This can change with time if the system gets distributed

• An alias name is available for each DP and can be used to simplify its tracking (e.g. if a device channel assignment changes within a detector)


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DCS Databases

• Two databases are essential for the DCS operation

• Configuration database stores : – Static settings (channel assignments, board

configuration…)– Dynamic settings (alarm limits, voltage set values,

FERO parameters…)

• DCS Archive stores: – Measured values– Alarms


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The DCS configuration database

• Configuration of all DCS devices is stored here

• Different versions (recipes) exist for different operation modes (calibration, cosmics, collisions…)

• Recipes can be changed during the operation (e.g. HV ramping through the intermediate state)


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The DCS Archive

• Designed to store measured values• Configured and accessed via the PVSS• Tools exists for mass configuration of archival

settings (smoothing, averaging, etc.)• All data written into the archive is timestamped• Only values read from devices are stored in the

archive (e.g. no direct data flow between the configuration database and the archive)

• Recipe versions are archived if the recipe is changed


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What data goes into the DCS archive?

• Only monitored values marked for archival are stored (DP config required). This includes:

• Data directly acquired by the DCS – HV, LV, FERO, magnetic field, environmental parameters, …

• External Data and Services – electricity, racks, DSS, LHC information, …

• ALICE specific information – run number, run type, …


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The DCS Data Flow

Config.

PVSS

Archive

DevicesDevices

DevicesDevices

ECS

Electricity

Ventilation

Cooling

Gas

Magnets

Safety

Access Control

LHC

DAQ TRI HLT

DIM, DIP


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DCS Archive implementation

• New method of PVSS archiving is finally available • The PVSS RDB archival is replacing the previous

method based on local files– All PVSS-based tools are compatible with the new approach (we

can profit from the PVSS trending etc.) – Oracle database server is required – Architecture resembles the previous concept based on files

• A set of Windows DLL’s and Linux libraries is used to access the archive from PVSS– Data storage and retrieval within the PVSS works without

changes

• A library handles the management of data on the Oracle Server (create/close tables, backup tables…)


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PVSS Archive Tables• For each group of archived values a set of tables is generated

– LastVal – input table storing the most recent value– Current – a table keeping a history record of measured values.

• An Oracle trigger is used to write data to this table• The table is closed if it exceeds a predefined size and is replaced with a new

one• The latest available values are copied to the new table automatically

– Online – a copy of the closed Current table– Offline – a table written to backup media and not directly available

• A set of internal tables for database maintenance exists• Archive tables are using their own tablespace (this is why a trigger

is needed)• For each Datapoint several parameters are stored:

– Value– Timestamp(s)– Flags (for example reliability)


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OnlineSPD

HistoryValues00000123

OnlineSPD

History00000123

OnlineSPD


OnlineSPD

History00000124

Basic DCS archive configuration

SPDLastValValues

SPDLastVal

CurrentSPD


CurrentSPD

History00000125

OfflineSPD


OfflineSPD


OfflineSPD

History00000011

OfflineSPD

History00000012

(arrays) (“basic” datapoints)


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Accessing the Archive Tables

• A set of libraries is available on the PVSS side to access the data from the database

• The libraries hide the archival complexity – user need to specify the Datapoint name and the time interval

• A dedicated library allows for direct database access (bypassing the PVSS managers)


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Example of Data Selection in PVSS (1)


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Generated SQLStatement

Result of thequery


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External access to the PVSS archive

• Database schema is available – data can be queried from external programs

• A set of basic Oracle views is provided by the ETM– The complexity of the table partitioning is

hidden

• A PVSS HTTP server allows for remote DP queries


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Root–to–PVSS interface

• Developed by V.Filimonov (ATLAS)• Allows for extraction of PVSS data into root• PVSS manager (GetArc) accepts requests from

clients, reads data from PVSS database and sends it to the client.

• A set of Root classes define the client protocol• Manager and Client interact via TCP/IP using

the PVSS API


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Root–to–PVSS communication

Example: get data for a given period of time

TPVSSAccess *sock = new TPVSSAccess("pcpix06.cern.ch",4242);

char *dp = "TestFloat1.floatvalue";

int rlen = sock->GetTimePeriod(dp,startTime,endTime,len,Values,ts);

Additional classes allow for displaying trends etc.

DP name Time Period

Length of data

valuestimestamps


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Root–to–PVSS example of trend

Online trend in PVSS

Online trend in Root


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Condition database developments

• The conditions database will store a subset of the archived data in a form convenient for offline processing

• JCOP framework is developing the interface to conditions database

• Conditions data will be written “on fly” by a dedicated process

• CMS, ATLAS and LHC-B plan to use COOL so all common tools will be available only for this architecture

• No developments for root are foreseen


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Present Status

• Prototype of the configuration database exists

• We are running a private Oracle server in the DCS lab

• First tests with RDB archiving performed, feedback provided to ETM

• We are aiming for a stable service during this summer (P2 and Lab)

the dcs databases

Documents

dcs devices

dcs hv

global dcs

data structure

simple system

distributed system

distrubuted system

distributed pvss system