Data and Computing Facility Operations
Facility Operations: Batch Systems bad examples
Do NOT do this, click here for good examples
5. How to I make sure my non-CRAB jobs are not accessing shared/NFS disk?
The LPC uses shared filesystems, /uscms/home, /uscms_data/d# and /uscmst1b_scratch/lpc1, between the worker nodes and the interactive nodes. Unfortunately, direct access to these shared filesystems from the workers can negatively affect performance for running jobs and more importantly for interactive users on the cmslpc nodes. The T1 team monitors for this activity and an automated system suspends ("holds") jobs when performance is slow and user jobs have too many open file descriptors to these shared filesystems. This short write-up is intended to help you avoid the NFS shared filesystems in your batch jobs.
Example #1: A Bad Example
This is an example of what not to do: this code will perform reads and writes on the shared filesystem directly from the batch job. It also changes the working directory right into the shared filesystem as well.Do NOT do this, click here for good examples
bad1.jdl (Note the use of the full path NFS to Output/Error/Log):BACK to good examples and batch documentationuniverse = vanilla Executable = bad1.sh Output = /uscms_data/d2/username/bad1.out Error = /uscms_data/d2/username/bad1.err Log = /uscms_data/d2/username/bad1.logbad1.sh (Note the cd to the NFS mounted data area):#!/bin/bash # cms software setup cd /uscms_data/d2/username root -b -q bad1.Cbad1.C (Note the use of the full path NFS):{ TFile f("/uscms_data/d2/username/input_file.root"); output_ntuples = process(f); // do some calculation TFile g("/uscms_data/d2/username/output_file.root", "w"); g.write(output_ntuples); }
