HowTo use EOS from the PSI Tier-3
Currently the local mounting of
EOS has problems. But we can use the command line
eos utility
For authentication
EOS accepts either a kerberos ticket or your grid proxy. So, you have to either do a kinit using your CERN account name and password
$ kinit cern_username@CERN.CH
or you do a normal
voms-proxy-init -voms cms -voms cms:/cms/chcms
Available
EOS endpoints
-
root://eoscms.cern.ch
: the main CMS namespace where you e.g. find /eos/cms/store/mc
and /eos/cms/store/user
-
root://eoshome-a.cern.ch
, root://eoshome-b.cern.ch
, ... : EOS home directory endpoints, one per username initial, where you can e.g. find root://eoshome-e.cern.ch//eos/user/e/exmpleuser
Define your endpoint in the EOS_MGM_URL environment variable or on the command line of the
EOS client commands. Here are some examples of eos cubcommands (ls, cp). There are more, consult the eos manpage.
EOS client commands:
export EOS_MGM_URL=root://eoscms.cern.ch
eos ls -l /eos/cms/store/test/loadtest/source/T2_CH_CSCS/urandom.270MB.file0001
-rw-r--r-- 2 phedex zh 270000000 Feb 20 12:06 urandom.270MB.file0001
eos cp /eos/cms/store/test/loadtest/source/T2_CH_CSCS/urandom.270MB.file0001 /scratch/feichtinger/test
[eoscp] urandom.270MB.file0001 Total 257.49 MB |====================| 100.00 % [97.8 MB/s]
[eos-cp] copied 1/1 files and 270.00 MB in 3.52 seconds with 76.62 MB/s
You can also use normal xrootd URLs to interact with the files from the command line or in your programs. This requires a grid proxy certificate for authentication (no kerberos). E.g. to interact with files in the home of my account dfeich, I can use:
xrdfs eoshome-d.cern.ch ls /eos/user/d/dfeich/testfile-df
# is equivalent to this
eos root://eoshome-d.cern.ch ls /eos/user/d/dfeich/testfile-df
xrdcp root://eoshome-d.cern.ch//eos/user/d/dfeich/testfile-df /scratch/feichtinger/mytest
EOS on local mounts - discontinued!
the local mounts are not working
We recommend using the
EOS client tools and direct xrootd protocol tools above. The FUSE (userland) mounting of
EOS may be convenient for local file management, but users tend to then also run massive code on the mounted filespace, while for those cases always the direct xrootd access should be used.
Currently CERN
EOS is mounted on the User Interface machines t3ui01-03:
$ ls /eos
home-a home-c home-e home-g home-i home-k home-m home-o home-q home-s home-u home-w home-y project
home-b home-d home-f home-h home-j home-l home-n home-p home-r home-t home-v home-x home-z user
to get access to your
EOS data, you first need to get a CERN kerberos ticket using the
kinit
command, which will ask you for your CERN password.
$ kinit cern_username@CERN.CH
Password for cern_username@CERN.CH:**********
You will now have a kerberos ticket allowing access to CERN services. You can list the ticket and information about it using
klist
:
klist
Ticket cache: FILE:/t3home/feichtinger/krb5cc_xyz
Default principal: dfeich@CERN.CH
Valid starting Expires Service principal
07.09.2023 17:50:39 08.09.2023 18:50:34 krbtgt/CERN.CH@CERN.CH
renew until 14.09.2023 17:50:34
To mount
EOS, you now just have to issue the following command
$ eosfusebind -g krb5 $HOME/krb5cc_$UID
Now you should be able to see your files by listing your
EOS mounted dir, e.g. for me
ls /eos/home-d/dfeich
Please observe that
EOS is not designed for high perfomance file access over the wide area network to CERN. You should not do intensive IO to
EOS from the Tier-3.