In large clusters, the large numbers of jobs results in a large number of job files stored in the LSF_SHAREDIR/cluster_name/logdir/info directory at any time. When the total size of the job files reaches a certain point, you will notice a significant delay when performing I/O operations in the info directory due to file server directory limits dependent on the file system implementation.
By dividing the total file size of the info directory among subdirectories, your cluster can process more job operations before reaching the total size limit of the job files.