Data management at T 3 s Hironori Ito

Data management at T 3 s Hironori Ito Brookhaven National Laboratory

Types • T 3 GS – Just like T 2 s • Pros: – Can use all available production software – Sites are monitored 24/7 • Cons: – Big overhead – Must be reliable • T 3 G – Not like other ATLAS sites • Pro – Minimum overhead – Reliability is not required • Cons: – T 3 s are on your own when problem exist. (sometimes)

US T 3 GS • GS Sites are in ATLAS Tiers of ATLAS. – It is operated by BNL T 3 DQ 2 SS – Requirements • SRM with space tokens • Must accept ATLAS production proxy (as they are). – No special, manual registration at a site. • Must pass a few tests – SAM test » lcg-cr, lcg-cp and lcg-del – ATLAS DDM functional tests • Must register at OSG OIM • Must publish to OSG BDII and CERN BDII via OSG Inter-op BDII – BNL publishes all SE only US T 3 s to OSG BDII. » T 3 must request to BNL (via DDM queue in RT) by providing its SE information • Must be able to respond to any ATLAS tickets within reasonable time.

T 3 GS Management • Use regular DQ 2 tools – Subsription • Da. TRI – Deletion • Central deletion • dq 2 -delete-replicas – Consistency • LFC is located in BNL for all T 3 • The content of LFC for specific T 3 is delivered to corresponding T 3 DDM site via DDM. – Sqlite format » Provide the fast search – Central catalog information » LFC has no dataset info.

T 3 GS Management (continue… I) • Use regular DQ 2 tools – Consistency • storage. Management. py – Work with the above LFC files – Scan local storages – Find SE and LFC dark files » SE dark files: exist in SE but not in LFC • Select * from files where pfn_se is not null and pfn_lfc is null » LFC dark files: exists in LFC but not in SE • Select * from files where pfn_se is null and pfn_lfc is not null – Delete dark files – Create logs » Log(s) is always created automatically. » All actions are stored in the log. – Obtain by » Svn checkout http: //www. usatlas. bnl. gov/ddmrepo/svn/repos/t 3 ddm » Download via browser at http: //www. usatlas. bnl. gov/ddmrepo/websvn/listing. php? repname=t 3 ddm

US T 3 G • Not in Tiers of ATLAS. – Can’t use DQ 2 SS • Requirement – Grid enabled SE • SRM or plain Gridftp server – Still register to OSG OIM • Difference with GS – No need to accept ATLAS production proxy – No tests to pass

Data Tools in US T 3 G • Use existing tools as much as possible. – Extend for future use • dq 2 -get and dq 2 -ls – Dq 2 -get • Plugins to use different transfer tools than lcg-cp – FTS plugins » Allow third party transfers between two remote SEs • Supports SRMs as well as Grid. FTP » Allow queuing » Avoid chaotic lcg-cp » New dq 2 -client package will include this plugin by default • The newest one is available at • svn checkout http: //www. usatlas. bnl. gov/ddmrepo/svn/repos/dq 2 plugin • Browswer download at http: //www. usatlas. bnl. gov/ddmrepo/websvn/listing. php? repna me=dq 2 plugin

Data Tools in US T 3 G (continue… I) • dq 2 -get and dq 2 -ls – dq 2 -get • Global name space – Dq 2 client developers are currently working on the change. – Store files with Global name space (LFC name space) » Same as LFC name space used in ATLAS production » Example • DSN: data 10_7 Te. V. 00165732. physics_Jet. Tau. Etmiss. merge. NTUP _JETMET. f 293_p 209_tid 172219_00 • LFN: NTUP_JETMET. 172219. _000799. root. 1 • LFC LFN global name space /grid/atlas/dq 2/data 10_7 Te. V/NTUP_JETMET/f 293_p 209/d ata 10_7 Te. V. 00165732. physics_Jet. Tau. Etmiss. merge. NTUP_ JETMET. f 293_p 209_tid 172219_00/NTUP_JETMET. 172219. _000799. root. 1

Data Tools in US T 3 G (continue… II) • dq 2 -get and dq 2 -ls – dq 2 -get • Global name space – Use of SE as a file catalog » T 3 G has no LFC » Easy extensions for other file transfer mechanisms • x. ROOTd-FRM • Find/transfer files with remote FRMs automatically • http(s) • Many SEs do/will support http/https currently and/or in the future • d. Cache/Best. Man/DPM • Make a new http plugins

Data Tools in US T 3 G (continue… III) • dq 2 -get and dq 2 -ls – dq 2 -ls • Global name space – dq 2 -ls currently requires LFC to find physical files – T 3 G has no LFC – dq 2 -ls will find physical files from the local(remote? ) SE according to the global name space. » Dq 2 developers are currently working on the change

Data Management at T 3 G • T 3 space must be managed by T 3 administrators with minimum helps from T 2 s/T 1 • No central replica catalog • No semi-central LFC • No need to synchronize – Just delete files from SEs as needed. – All files in a given dataset are stored in one particular directory according to the global name space. • delete-replica DSN rm –rf /A/B/…/DSN • List-datasets-site SITE ls –R /base-data-directory

Thought on Global Name Space • Great way to avoid local catalog – Cons: Performance issue on SE to list files? • Expand the methods to access files – x. Rootd FRM – http/https: • http/https is much easier, and has wide standard support • Everyone knows how to use browser • Many clients: – wget works everywhere. – Aria 2 (http: //aria 2. sourceforge. net/) » Segmented download • Stop-start transfer in the middle • Use of multiple source sites for a single file • Use of multiple streams from the single source hosts per single file • Use of multiple downloads. » Casual test: • Wget at 4 MB/s <-> aria 2 at 60 MB/s – LFC+d. Cache+http demos at • http: //www. usatlas. bnl. gov/lfc/metadatas/ls? lfn=/grid/atlas/dq 2