HowTo EOS

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

Export a standard access point for the EOS system you want to target

export EOS_MGM_URL=root://eoscms.cern.ch

Now you have a number of file commands available (look at eos manpage), e.g.

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

EOS on local mounts CURRENTLY THERE ARE PROBLEMS

the local mounts are currently not working

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.