Computing

CERN ressources are available to be used by people being employed by an institute that has signed the Memorandum of Understanding (MoU) and by laboratories having signed the Addendum. For more information on the procedure please have a look at FCC PED Official Documents.

The computing and disk resources are controlled by dedicated CERN e-groups with admin approval.

Those receiving approval engage in using these resorces ONLY for activities related to FCC.

Computing resources

A quota of resources, dedicated to FCC computing activities, are available in the HTCondor-based CERN batch farm. Use of these resources is controlled by the CERN e-group fcc-experiments-comp and subject to admin approval. The associated accounting group is group_u_FCC; to use resources from this quota, the following needs to be added to the HTCondor job sumbmit file:

+AccountingGroup = "group_u_FCC.local_gen"

Storage resources

Disk space volumes for storage, dedicated to FCC computing activities, are available in the EOS system at CERN under the paths

/eos/experiment/fcc
/eos/experiment/fcc/ee/analysis_storage

Read access to these resources is controlled by the CERN e-group fcc-eos-access and subject to approval. Note that e-groups fcc-eos-read-prod, fcc-eos-read-ee, fcc-eos-read-hh, fcc-eos-read-hh-sm21 and fcc-eos-read-eh still exists for internal usage but they have been closed to self-subscription.

Write access to these resources is controlled by a fine-grained number of CERN e-groups and subject to approval. Please contact the software and computing coordinators or physics groups conveners for specific requests.

Access to storage resources from outside CERN

Users enabled to access the FCC area on EOS can do so also from outside CERN using the Kerberos credentials associated with their CERN user account. To do so, they have to make sure to have the Kerberos credential initiator application, kinit, installed and configured to enable the CERN.CH Kerberos realm. Typically is enough to copy the relevant sections from the /eos/krb5.conf file accessible on lxplus (or copying the complete file, if there is none locally or if the local one is not customized).

Once this is done, the following should work:

$ kinit ganis@CERN.CH
ganis@CERN.CH's password:
(Enter CERN lxplus password)

$ klist
Credentials cache: API:68FEEF0D-F635-45C6-91B3-1A7A6F83E0C6
        Principal: ganis@CERN.CH

  Issued                Expires               Principal
Dec  2 16:20:16 2020  Dec  3 17:20:10 2020  krbtgt/CERN.CH@CERN.CH

The files can be copied locally

 $ xrdcp root://eospublic.cern.ch//eos/experiment/fcc/ee/generation/DelphesEvents/fcc_v02/p8_ee_ZH_ecm240/events_199832436.root .
[80.67MB/80.67MB][100%][==================================================][16.13MB/s]

or accessed directly via ROOT

$ root -l
root [0] auto f = TFile::Open("root://eospublic.cern.ch//eos/experiment/fcc/ee/generation/DelphesEvents/fcc_v02/p8_ee_ZH_ecm240/events_199832436.root")
(TFile *) @0x7ffee5b6b718
root [1]

Note the use of the eospublic.cern.ch server. A cache system, for example based on XCache, can make the whole setup more efficient.

Another possibility is to mount the remote directory locally using the sshfs utility, for example

$ mkdir ~/eosfcc
sshfs -o idmap=user -o follow_symlinks ganis@lxplus.cern.ch:/eos/experiment/fcc /home/ganis/eosfcc
(CERN lxplus password)

The local and remote user and group ID must be the same for this to work.

FCC Software Meetings