Access to DST files on HADES event builders

Due to the fact that the Hera file system is only visible to a limited number of computers, we decided to have a copy of selected files on our own servers: The Eventbuilder in the counting house have roughly 200 TB of storage which is mostly unused in between beam-times. First, a few notes:

  • The bandwidth of all servers is limited to 10 GBit/s and the link to desktop PCs is 1 GBit/s only. So, don't expect too high performance.
  • Not all files are available at the moment, roughly 5% of files are missing.
  • During beam-times and other activities, access to some or all of the servers will be limited.
Getting Access

To get access to the servers, send your ssh key to one of the responsible people. For them, there is an automatic script available in /misc/hadaq/diskcluster/ If you don't know how to obtain the key:

  • The key can be found in the file ~/.ssh/ in your user account
  • If it doesn't exist, run ssh-keygen first. Answer all questions by pressing the enter key.
Mounting the Filesystem
  • All files will be available in a sub-directory called 'hadesfiles' on your machine. First, go to the directory where this sub-directory should be created.
  • Run /misc/hadaq/diskcluster/
    When running this script for the first time, you are required to type 'yes' five times.

The files in hadesfiles are stored in 5 sub-directories which are again sub-divided in up to 22 sub-sub-directories - This is our structure of servers and disks.

Hints & Tricks
  • You can create a file list for your script by running:ls -1 hadesfiles/*/*/*.root | sort -R > file.list
    The last * can be replaced by any filter you like, e.g. '*be12100*' to have only files from day 100.
  • Only Apr12 Gen1 DST files are available at the moment, others can be copied by request.
  • In the future there might be a possibility to run scripts on one 64-core server machine for "medium-sized" analysis.
  • There is no user space forseen on these machines (at least not now), files have to be stored locally.