Configuring a small PROOF cluster

Dear All,

I’m trying to configure a small PROOF cluster (currently containing two machines), but I’m stuck. Maybe someone here will be able to help. (With Gerri still on holiday. :wink:)

I have two PCs in my office, one quad-core, pretty high-powered one, and a pretty old one. I’m just using the second one as a “proof of concept”. (No pun intended… :stuck_out_tongue:) I’ve set up single machine “PROOF clusters” before, because I wanted to be able to send jobs to a machine from multiple other machines. That always worked well. Now I’d like to achieve the following setup:

  • The bigger machine should act as a master, and it should also run 4 worker threads.
  • The smaller machine should run one worker thread.
  • The bigger machine has a big external disk that should be visible to all the nodes in the same way. (Only read access.)
  • Both machines should have some local storage for the output of using TProofOutputFile.

I’ve created a configuration which you can find under


PROOF actually seems to work, but when my application tries to collect the output ntuples from the worker nodes, it complains that it can’t access

root:// … 9beef.root

( is the “smaller” machine.)

So the smaller machine is definitely not acting as a file server toward the master. I’m trying to find the solution in the online PROOF documentation, but these configuration issues are not described all that well I’m afraid. (At least I always make my configuration in a trial-and-error fashion…)

You can find the full logfile of this under


Any help would be much appreciated.


For the record, attached is a configuration file that solved Attila’s problem.

Gerri (1.23 KB)

Hello Gerri & Attila

I have the same problem: when trying to merge, the master doesn’t manage to retrieve the files located on the slave nodes.

example: the master is ccapl0001 , it is trying to fecth a file on ccapl0003

TProofOutputFile::AddFile: error from TFileMerger::AddFile(root:// … 6//Pt.root)

I have tried the config file posted by Gerri, trying every option line by line, but it doesn’t help.
What is the relevant line for this special case ?

Also, there is one thing I don’t understand : what is supposed to do the /pool0 directory ?
It is relevant for this matter ?

Many thanks !