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Duke and ANL ASC Tier 3
(stand alone Tier 3’s)
Doug BenjaminDuke University
ANL ATLAS Analysis Center“prototype” Tier 3
Used to develop all of the scripts needed to setup a Tier 3 site –
Used to test tools and software to train others Expect it to grow as the number of users at the ASC
increases
Developing puppet configurations at this site
Supported by DPB (very part time)
Use Xrootd.org Yum repository for most libraries
OSG Yum repository for the gridftp bits
“baseline” Tier 3g public/private networks
Head = redirector
Standalone xrootd data server
Xrootd data servers all on private network only
Clustered xrootd storage
Head Node/Redire
ctor
Stand alone Xrootd data
server
worker Node/ xrootd
data server
worker Node/ xrootd
data server
worker Node/ xrootd
data server
Private network
Xrootd clustered storage(private network)
Baseline Tier 3 (public/private network)All data access within cluster (LAN) via private networkUse case 2. – storage on worker node data servers as part of Federation
Physical machine w/ local xrootd functionality
Overlay xrootd functionality
Public IP network
Head nodexrootd Proxy
(public network)
Head node -Xrootd read-only redirector(privat
e network)
Xrootd read-only data
server(private network)
Xrootd read-only data
server(private network)
Xrootd read-only data
server(private network)
Outgoing read only data flow
Xrootd configurationWiki page with example configuration
https://twiki.cern.ch/twiki/bin/view/Atlas/Tier3gXrootdSetup
Know issues“sss” xrootdfsFrm checksuming turned off - Due to configuration
of the data servers (oss.localroot).
Duke Tier 3Support
Department system admin’sDPB (very part time)Puppet helps reduce the loads
Disk heavy worker nodes and on big file server (SL 6)Stand alone SL 5 gridftp server (used a proxy
server)
Use Xrootd.org Yum repository for most libraries
OSG Yum repository for the gridftp bits
Head Node/Redire
ctor
Stand alone Xrootd data
server
worker Node/ xrootd
data server
worker Node/ xrootd
data server
worker Node/ xrootd
data server
Xrootd clustered storage
Public network version of Baseline Tier 3Use Case C. - data from all data servers (WN and stand alone)
Physical machine w/ local xrootd functionality
Overlay xrootd functionality
Public IP network
Head node -Xrootd read-only
redirector
Xrootd read-only data server
Xrootd read-only data server
Xrootd read-only data server
Xrootd read-only data server
Outgoing read only data flow
Outgoing read only data flow
Information flow to global redirector
Xrootd usage at DukeUsers begrudgingly are using Xrootd
More senior folks like to use NFS like accessThen to use xrootdfs to access the storage
Graduate students much more adaptable.
