1. Integrating SRB with the GIGGLE framework
Simon Metson
Owen Maroney
Tim Barrass
ACAT ’03, KEK, Japan
Hello, my name is Simon Metson. My colleagues and I are members of the Particle Physics group at Bristol in the UK.I’m here today to talk about a project that my colleagues and I have been developing.
We’ve been giving some thought to how the SDSC’s Storage Resource Broker might interoperate with the European DataGrid. We’ve identified three components to this system, and today I’m going to talk about the first- the integration of the SRB with the GIGGLE framework.
24/02/2019

2. The GIGGLE Framework Chervenak et al, http://www. globus
Generic distributed data discovery system
High level of redundancy, failover
EDG/LCG and Globus are both developing implementations
RLI
LRC
Framework proposed by Chervenak et al
Generic system of data discovery
Based on a hierachy of services to avoid a single points of failure
SE register PFN:GUID mapping in LRC
LRC pushes GUID:LRC mappings onto RLI
RLI forwards queries to relevant LRC
LRC returns PFN
EDG/LCG and Globusboth developing implementations
24/02/2019

3. Storage Resource Broker SDSC, http://www.npaci.edu/DICE/SRB
Integrated data distribution tool
Presents a single abstracted file space composed of distributed resources
Tape, disk, compound resourses
Produced by SDSC
~5 years old – maturing product
Used by many large projects (including CMS for its recent Monte Carlo pre-production)
MCat
SRB
24/02/2019

4. The Aim Could files stored in SRB be accessed by Grid tools?
Interoperability is one of the key benefits of grid middleware!
Extend (not replace or modify) tools available to user
Active collaboration between members of CMS, BaBar and the SDSC SRB Group
Scenarios:
Data discovery – locating SRB files using RLS
Job submission – publish resource information and send jobs to farms with ‘close’ SRB servers
File replication – consistent copying of files to and from SRB using grid tools
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5. Data Discovery
Grid uses GIGGLE framework to publish data management information
RLI
LRC
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6. Data Discovery RLI MCat LRC SRB
Grid uses GIGGLE framework to publish data management information
RLI
LRC
SRB uses MCat database
MCat
SRB
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7. Data Discovery RLI RLI MCat LRC LRC SRB SRB GMCat MCat
Create LRC interface to MCat - GMCat
MCat
SRB
RLI
LRC
GMCat
Grid uses GIGGLE framework to publish data management information
RLI
LRC
SRB uses MCat database
MCat
SRB
24/02/2019

8. Implementation Plan … Proof of concept prototype complete LRC GMCAT
Sync LRC with MCAT contents
Test namespace mapping
MCAT /zone/user.domain/my/path/myFile
LRC srm://hostname/a/path/theFile
Not performant
Compares the whole MCat database using “Scommands”
New functionality of next SRB release expected to improve this
Time stamping – reduces number of files to check
GUID generated automatically – attaching GUID metadata is slow
LRC
push
GMCAT
pull
MCAT
Extended workshop with SDSC, who took on board our ideas
SRB files located by Dataname and replica number
Dataname is unix like path
Replica number enumerates replicas
LRC SURL has hostname, path and file, and scheme
Scheme will be srb
Need to extract hostname from SRB
Create path from dataname and repl_enum
To make mapping
Generate SURL and GUID
Store GUID in MCAT for consistency
Push SURL:GUID mapping onto LRC when synching
NEXT!!! Go through the mapping in detail, following slides
24/02/2019

9. The Prototype In Detail
User puts file into SRB with SRB client
$ Sput myfile.txt /phy.bris.ac.uk/home/srbadmin.phy.bris.ac.uk/test/myfile.txt
$ ./server_interface.pl
guid = e4fb1ff3-ae4f-4e38-9b a15a92d8
$ edg-lrc -i mappingsByPfn --vo srbrls -h tuber15.phy.bris.ac.uk \
"*/phy.bris.ac.uk/home/srbadmin.phy.bris.ac.uk/test/*"
guid:e4fb1ff3-ae4f-4e38-9b a15a92d8,
srb://tuber13.phy.bris.ac.uk/phy.bris.ac.uk/home/srbadmin.phy.bris.ac.uk/test/myfile.txt_0
24/02/2019

10. The Prototype In Detail
User puts file into SRB with SRB client
$ Sput myfile.txt /phy.bris.ac.uk/home/srbadmin.phy.bris.ac.uk/test/myfile.txt
$ ./server_interface.pl
guid = e4fb1ff3-ae4f-4e38-9b a15a92d8
$ edg-lrc -i mappingsByPfn --vo srbrls -h tuber15.phy.bris.ac.uk \
"*/phy.bris.ac.uk/home/srbadmin.phy.bris.ac.uk/test/*"
guid:e4fb1ff3-ae4f-4e38-9b a15a92d8,
srb://tuber13.phy.bris.ac.uk/phy.bris.ac.uk/home/srbadmin.phy.bris.ac.uk/test/myfile.txt_0
GMCat updates LRC
24/02/2019

11. The Prototype In Detail
User puts file into SRB with SRB client
$ Sput myfile.txt /phy.bris.ac.uk/home/srbadmin.phy.bris.ac.uk/test/myfile.txt
$ ./server_interface.pl
guid = e4fb1ff3-ae4f-4e38-9b a15a92d8
$ edg-lrc -i mappingsByPfn --vo srbrls -h tuber15.phy.bris.ac.uk \
"*/phy.bris.ac.uk/home/srbadmin.phy.bris.ac.uk/test/*"
guid:e4fb1ff3-ae4f-4e38-9b a15a92d8,
srb://tuber13.phy.bris.ac.uk/phy.bris.ac.uk/home/srbadmin.phy.bris.ac.uk/test/myfile.txt_0
GMCat updates LRC
File is visible through LRC
24/02/2019

12. Implementation Plan… Developing production system prototype
Modifications & further testing required to ensure correct operation within production environment
Include features of future SRB releases as they become available
Possible use for upcoming CMS Data Challenge
LCG POOL objects stored in SRB space
Need to access them via an EDG LRC…
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13. Future Implementation
Move to webservice implementation
Match EDG LRC interface
Provide dynamic mapping of MCAT to EDG RLS namespace
No large database queries
More maintainable code
No production ready RLI currently available
CMS intend to use single LRC for DC04
Currently this means we’ll not be able to use the dynamic webservice, unless MCat stores other LRC data
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14. The Complete System
Will need to address information publishing and file replication
Former straightforward- SRB servers can publish in the same way as an EDG Storage Element
Latter difficult
SRM interface to SRB?
Most elegant, but there are difficulties
gsiFTP server on SRB?
Problems- that SRM is designed to solve
EDG Replica Manager talks to SRB natively?
Not as generic a solution as interface like SRM
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15. Conclusion SRB and the EDG/LCG can interoperate
Data Discovery component well understood, and useful in isolation
Full interoperation requires some development effort
Great interest from BaBar, SDSC, CMS and RAL on various aspects so far
Website in production at
10,000 new files takes ~45 minutes on a low-spec MCAT box
If no files have been added to a list of 10,000 files, synch takes 4 minutes
Isn’t this what a fed MCAT does?
Difference in EDG / Globus RLS?
Timescale for completion of Data Discovery? Full system?
What are the difficulties in implementating an SRM interface?
Why is a gsiFTP server bad?
Are you intending to replace the EDG SE?
24/02/2019