lezione n. 16 - INFN - Napoli

Transcript

Griglie computazionali
Università degli Studi di Napoli Federico II
Corso di Laurea Magistrale in Informatica – I Anno
LEZIONE N. 16
•
FTS - File Transfer Service
•
Grid Accounting: APEL e DGAS
Griglie Computazionali
- aa 2008-09
Introduzione alle griglie computazionali
aa 2006-07
1
Introduzione
In questa lezione esaminimo due argomenti distinti:
• Il File Transfer Service, un servizio di trasferimento dei
file che completa l’argomento della gestione dei dati
(lez. 10 e 11)
• I sistemi per l’accounting in Grid, ossia i meccanismi
per determinare l’utilizzo effettivo delle risorse da parte
degli utenti e delle VO.
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Trasferimento dati controllato dal
client
• Nei primi strumenti di trasferimento dati (gridftp) la copia è
controllata dal client.
Client
Source Storage
Element
Data Flow
Channel
•
•
Control
Channels
Destination Storage
Element
Anche se I protocolli di trasferimento sono robusti, ciò pone delle
limitazioni: lo stato del trasferimento è “nascosto” .
Il client conosce internamente lo stato locale, ma non sa nulla dello
stato globale dei trasferimenti tra gli storage element coinvolti
– Gli Storage elements posso essere sovraccaticati da richieste
– Posso avvenire simultaneamente repliche multiple degli stessi dati
– Non c’e controllo sull’utilizzo globale della rete
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Servizio di Trasferimento Dati
•È necessario un servizio per
gestire il data transfer
– Il Client si connette al servizio per
sottomettere una richiesta
– Il Service è a conscenza dello
stato dei trasferimenti
– Il Client può periodicamente
riconnettersi per controllare lo stato
o cancellare una richiesta
– Il Servizio è a conscenza dello
stato globale, non di una singola
richiesta, quindi puo’ effettuare:
•Load balancing
•Scheduling
•Submit new request
•Monitor progress
•Cancel request
Client
SOAP via https
Transfer
Service
Source
Storage
Element
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Data
Flow
Destination
Storage
Element
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File Transfer Service
• File Transfer Service (FTS) e’ un servizio per il
trasferimento di dati
E’ un servizio multi esperimento, utilizzato per bilanciare l’uso delle
risorse di un sito in accordo con le policy del sito stesso e delle
Virtual Organizzation (VO) che supporta;
• Perche’ serve?
– Lato utenti, il servizio permette il trasferimento dei file da una
sorgente ad una destinazione in modo affidabile;
– Lato site manager, fornisce una soluzione affidabile ed
elastica per soddisfare le richieste di trasferimento dati
provenienti dagli esperimenti supportati;
– Lato production manager, permette di controllare le richieste
dei loro utenti (priorita’, re-schedule transfer, ….)
• Il focus e’ nel “servizio”:
Deve permettere queste operazioni in maniera semplice e
trasparente
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Archiettura di File Transfer
Service
•
I Client sottomettono jobs via
SOAP su https.
•
I jobs sono liste di URLs in
formato srm:// . Si possono
specificare alcuni paramtri del
trasferimento (stream parallele,
buffer sizes).
•
I Client possono richiedere
informazioni sui cambiamenti di
stato del trasferimento.
•
C command line clients. C,
Java and Perl APIs available.
•
Il servizio si presenta come un
Web service in Tomcat5.
Client
Secure web service
connection
Transfer
Service
Well defined
state
transitions/
checkpointing
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Storage
Elements
Database
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Note
SOAP - The Simple Object Access Protocol provides a means of
messaging between a service provider and a service requestor.
SOAP is a simple enveloping mechanism for XML payloads that
defines a remote procedure call (RPC) convention and a
messaging convention. SOAP is independent of the underlying
transport protocol; SOAP payloads can be carried on HTTP, FTP,
Java Messaging Service (JMS), and the like. We emphasize that
Web services can describe multiple access mechanisms to the
underlying software component. SOAP is just one means of
formatting a Web service invocation.
Apache Tomcat is the servlet container that is used in the official
Reference Implementation for the Java Servlet and JavaServer
Pages technologies.
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Canali FTS
• Il Servizio FTS ha il concetto
di canale
• Un canale è una connessione
unidirezionale tra due siti.
•
•
•
Le richieste di trasferimento tra
questi I due siti sono assegnate al
corrispondente canale
I canali accettano le wildcards:
– * to MY_SITE : All incoming
– MY SITE to * : All outgoing
– * to * : Catch all
I canali a volte corrispondono
connessioni di rete dedicate a una
particolare produzione, ma non sono
connessioni fisiche.
• Channels control certain
transfer properties: transfer
concurrency, gridftp streams.
• Channels can be controlled
independently: started,
stopped, drained.
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File Transfer Service
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gLite FTS: Agenti
•
Ogni job sottomesso a FTS
passa attraverso un VO Agent
e un Channel Agent.
Channel Agent
•
•
VO Agent
•
•
Gli effettivi trsferimenti sui
canali sono gestiti dal channel
agent
I Channel agents possono eseguire
uno scheduling inter-VO
L’agente della VO autorizza il
job e cambia il suo stato in
“Pending”
I VO agents possono compiere
altre operazioni specifiche
della VO:
– Scheduling
– Interazione con il File
catalog della VO
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FTS schema generale
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Utilizzo di FTS
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Conclusioni
•
FTS offer an important and useful service on the grid – a
significant advance on client managed file transfers.
•
FTS channel architecture offers very useful features to control
transfers between sites or into a single site, though it may become
overly complex in a grid without clear data flow patterns.
– The ability to control VO shares and transfer parameters on a
channel is important for sites.
•
FTS agent architecture allows VOs to connect the transfer service
closely with their own data management stacks, a useful feature
for HEP experiments.
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Why Accounting ?
In a distributed computing environment people want
to know who used the resources and how many
resource have been used.
• Users : How many resources am I using ?
• VO managers : how many resources is my VO
using ?
• Site Managers : who is using my resources ?
• ROC Managers : How many resources have
been used in my federation and who used them ?
A good accounting system should be able to answer
these questions taking care of all the security and
privacy issues.
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Grid accounting
Una generica infrastruttura di grid accounting deve coprire i requirements
di tre tipi di utenti: Siti, VO ed amministratori grid .
grid layer
Users/VO layer
Site layer
Resource’s layer
grid accounting database
VO accounting database
Site accounting database
Usage Metering
Introduzione alle griglie computazionali aa 2006-07
Web reports:
-Aggregate info
-Sites load
-Anonymised statistics
-Aggregate VO info
-Group/Role info
-Detailed User info
-Job level info
-Aggregate site info
-VO (with role/group)
usage on the site.
-Detailed Resource Usage
info
-Job level info
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CPU Accounting
• Consiste nel raccogliere e registrare secondo metriche
predefinite, informazioni sulla disponibilià e l’utilizzo delle risorse
di calcolo, o di grandezze derivate.
• Le sorgenti di informazione primarie sono i log files di :
•CE gatekeeper + batch system
Storage Accounting
• Consiste nel raccogliere e registrare secondo metriche
predefinite, informazioni sulla disponibilià e l’utilizzo delle risorse
di storage
• Le sorgenti di informazione primarie sono i log files di :
• transfer services + storage system
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Sistemi per l’accounting in grid:
• DGAS (Distributed Grid Accounting System) è un sistema di
distribuito capace di effettuare la misurazione dell’utilizzo delle
risorse ed eventualmente un Accounting Economico.
È basato su una infrastruttura client/server basata su una rete
di server di accounting indipendenti.
Sviluppato nell’ambito EGEE dalla sezione di Torino dell’INFN.
• APEL (Accounting Processor for Event Logs) è un
componente dell’ EGEE CPU Accounting system, distribuito
come parte del gLite middleware.
APEL pubblica i record di utilizzo delle CPU in grid in una
repository centralizzata, il GOC (Grid Operations Centre)
usando R-GMA come meccanismo di transporto.
I records sono processati e possono essere acceduti
attraverso l’EGEE Accounting Portal.
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Requirements / Use cases
How much resource has been provided to each VO?
Grid Level (High Level)
How much resource has been provided to each VO
Grid Level (High Level) Aggregation / Data Consolidation
Administrative Domains :VOs, VOMS Groups, Countries (LHC), Regions (EGEE)
Grids, (EGEE, OSG, TeraGrid, Nordic)
Organisations (GridPP, INFNGrid, SEEGrid, …)
If 10,000 CPU hours were consumed by Atlas VO, who are the users that
submitted the work?
Finer Granularity (Low level)
User Level, Job Level, Top Users within a VO and Group
Confidentiality
Quota enforcement / fairshare scheduling: how much resource has been
provided to a particular user on a particular set of CEs?
User Level, Job Level
Confidentiality
Reliability
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DGAS Components
• Sensors on CEs
– Build usage records from LRMS accounting
files
• Resource (site) HLRs (Home Location Registers)
– Collect usage records from one or more sites
• User (VO) HLRs
– Collect usage records for a whole VO
• Query clients and visualization tools
– Allow to retrieve data from HLRs
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DGAS Workflow
Usage Record
3
L2 HLR
3
Usage Record
3
VO HLR
Site HLR
CE
1
job
2
job
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DGAS Features
• Granularity
– Resource accounting at single job level or in aggregate form per user,
per VO, per resource (site) or per infrastructure (collection of sites).
• Scalability
– Arbitrary number of Resource/VO HLRs can be deployed.
• Hierarchical Design
– HLRs can be interconnected, in order to have multiple levels of
aggregation.
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DGAS Features II
• Completeness
– Capability to collect information both for grid and local jobs.
• Customization
– Possibility to choose which resource and/or type of jobs must
be accounted.
• Designed to perform pricing (not used)
– Possibility to assign “computing credits” (something similar to
quotas) that can be used as a basis for billing the resource
consumptions.
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DGAS
features
Site sensors
•
•
•
•
can build accounting records for grid jobs as well as local jobs
(accounted on different HLR accounts)
for grid jobs: integrates local usage information with grid-related
information (user DN, user FQAN (VOMS), CE ID, grid job ID).
supports PBS and LSF
“next-to-real-time” accounting (after job completion)
Client (UI)
HLR service (accounting servers)
• fully distributed architecture (scalability)
• deployed as User (VO) HLRs and/or Resource (Site) HLRs
• command line tools and C++ API for queries
• strict authorization control (x509) for accessing private info
VO HLR
Site HLR
Data transport:
• all communication between the components as well as between client
tools and servers is encrypted and secure (x509-based, GSI)
•
CE
mostly asynchronous data transport between the components for more
robustness
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Information retrieval
• Information are retrieved parsing the LRMS (batch system)
accounting log files and the CE gatekeeper log file
• LRMS log files :
•resource used (cpu-time,wall-time,lrmsid,user,group)
• Comuptin Element gatekeeper log files :
•grid info (user DN, grid-jobid,VO)
• Some other config files are used in order to manage local jobs,
for which the VO could not be defined through the proxy
certificate.
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Security and Privacy
• Information confidentiality is guaranteed by the use of
different authorization levels to access the Usage Records.
– Users (can access their own detailed records and aggregates)
– Site Managers (Can access their own site detailed records
and aggregates)
– VO Managers (Can access detailed records and aggregates
of all VO members)
• Full VOMS integration in query authorization is available
(now on L2 HLR, on every HLR in future releases)
– (e.g. /atlas/Role=vomanager/Group=NULL)
• Security and integrity of the data flow is guaranteed by the
use of GSI and data encryption.
• No sensitive information sent in clear text
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Accounting & policies
The accounting information can be also used to implement dynamic
resource access policies and help in fair sharing of available
resources.
It is clear that in order to reach this goal is necessary to have real
time access to accounting information.
It is also necessary to be sure that the information contained in the
accounting databases can’t be maliciously altered by the users
(reliability).
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APEL features
Three Components:
Sensors (Deployed at site) :• Process log files; maps DN to Batch Usage; builds accounting records
• Accounts from Grid Jobs Only
• Supports PBS, SunGridEngine, Condor, and LSF
• Not REAL-TIME accounting
Data Transport:• Uses RGMA to send data to a central repository
• 196 sites publishing, 7.5 Million Job records collected
• Can use other transport protocols
• Allows sites to control DN information from leaving site
Presentation (GOC and Regional Portal)
• Reporting based on data aggregation
• LHC View, EGEE View, GridPP View, Site View
• Metrics (e.g. Time Integrated CPU Usage)
Introduzione
alleCharts,
griglie computazionali aa 2006-07
Tables,
Pies, Gantt
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APEL Issues
Data Privacy and Confidentiality
• Provides sites with the option to publish or suppress (default) DN
information
– Many sites suppress DN, some sites publish DN.
• Any person with a trusted certificate and access to a UI can
query RGMA and get Job Record information from APEL
database
– x509-based authorization features in RGMA in development
• Does not currently encrypt the usage record
• Does not currently sign the data
General Issue For Accounting: Normalisation in Heterogeneous
Farms
• APEL Uses SpecINT2000 published by sites in the information
system because sites have different strategies/policies for
setting up their batch systems
– Some sites publish SI2K of slowest worker nodes
– Other sites publish a weighted mean, because they use internal
scaling factors
– Many Batch systems currently in use don’t report
performance/benchmark information of the worker nodes in the
batch logs.
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APEL + DGAS
When used together APEL and DGAS can leverage each others
strengths and give to their customers the following benefits:
• Fully distributed architecture
• From single job to grid-level accounting information.
• Web access to aggregate usage information.
• VOMS based accounting (using VOMS FQAN in usage records).
• Real time access to job accounting info for users and site
managers.
• Security and authorisation mechanisms to guarantee information
integrity and confidentiality.
• Possibility to access non-confidential information via RGMA.
APEL and DGAS, if used alone, have their own specific strengths
and limitations.
None of the two can fulfill the previously highlighted requirements
for grid accounting.
However, APEL and DGAS have complementary functionalities that
if used in sinergy actually can fulfill the requirements.
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APEL + DGAS (2)
DGAS and APEL as components of the vertical
accounting infrastructure (DGAS2APEL example)
grid layer
Users/VO layer
Site layer
Resource’s layer
APEL and GOC web interface
DGAS VO HLR
DGAS site HLR
Accounting Sensors (joint)
Web reports:
-Aggregate info
-Sites load
-Anonymised statistics
-Aggregate VO info
-Group/Role info
-Detailed User info
-Job level info
-Aggregate site info
- VO (with role/group)
usage on the site.
-Detailed Resource Usage
info
-Job level info
30
DGAS2APEL workflow
R-GMA
R-GMA
dgas2apel
HLR DB
apel-publisher
HLR
LCGRecords
GOC DB
• Dgas2apel is a process that converts the Usage
Records from the format adopted by DGAS to the one
adopted by APEL. Converted records are then
inserted in a RDBMS table known as LCGRecords.
• Such records are then forwarded to the GOC by
APEL itself via its ‘apel-publisher’ process, which
uses RGMA as a high level transport service toward
the GOC.
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Examples
Multi Site Information from L2 HLR
Jobs per site (T1 included)
Jobs per VO (T1 included)
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Examples
Multi Site Information from L2 HLR
Jobs per day
(T1 included)
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Referenze
• File Transfer Service FTS:
http://egee-jra1-dm.web.cern.ch/egee-jra1-dm/FTS/
• APEL accounting website:
http://goc.grid.sinica.edu.tw/gocwiki/ApelHome
• DGAS website:
http://www.to.infn.it/grid/accounting/main.html
• DGAS User Guides:
https://edms.cern.ch/document/571271/1
34

lezione n. 16 - INFN - Napoli

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