Navigating the Root Directory

This page explains how the file system is set up, and where the various pieces of the system live.

Let's look at the root directory on a slave:

bin	data	etc	initrd	ldas_outgoing	lib	misc	net	opt	root	scratch	usr
boot	dev	home	ldas	ldcg	lost+found	mnt	netdata	proc	sbin	tmp	var

The directories bin   dev   lib   lost+found   misc   proc   root   sbin   tmp   usr are used in the normal Red Hat way and should be familiar to anyone doing system administration on the beowulf.

The following directories are special:

• boot
  This directory contains the kernel and files used by lilo. It also contains an initial ram disk image that can be used to boot the system with its root filesystem over NFS. The modules for the kernel are found in /lib/modules/KERNELVERSION/ where KERNELVERSION is the full version number of the kernel installed (e.g. 2.4.19-1medusa). The kernel and modules are installed as RPMS and should be managed as such.
• data
  This is where UWM's current LIGO data resides. Each slave has different parts of the data.
• etc
  This directory contains the system configuration files. A lot of the custom RPMS that we have made (such as the UPS software) place their config files in here.
• home
  The directories search01 to search16 reside here.
• ldas
  This directory contains the LIGO Data Analysis System (LDAS) software. It is mounted from uwmlsc.
• ldcg
  This directory contains the LIGO Data Computing Group (LDCG) software. It is installed as a single RPM on each slave. There are a number of different packages installed in the RPM. It contains software with specific versions and patches for use with LDAS. To use this software, add the contents of /etc/ldcg.sh or /etc/ldcg.csh to your bash_profile and/or bashrc or cshrc as appropriate.
• mnt
  This directory is managed by automount. It contains the following virtual mount points:
  1. scratch
     Scratch space for users of the cluster.
  2. 7.3install
     Files relevant to the installation process on the slaves and masters.
  3. backup
     Files relevant to backing up important user account information. Proceed with caution.
  4. ldas
     This directory contains the LIGO Data Analysis System (LDAS) software.
  5. ldas_outgoing
     This directory contains files relevant to the the LDAS software.
  6. mail
     This is the groups mail spool.
  7. floppy
     A mount mount for floppies formatted with the ext2 file system.
  8. floppy_msdos
     A mount mount for floppies formatted with the MS-DOS file system.
  9. cdrom
     A mount mount for the CD-ROM drive for disks formatted with the ISO9660 file system.
• net
  This directory is managed by automount. It contains mount points for the root filesystem of every slave and master. The directories are named:
    /net/s001 ... /net/s320 for the slaves.
    /net/m001 ... /net/m003 for the master.
• opt
  This directory should contain any software that is installed on each node, but is "non standard". This includes software such as MPICH or condor. Each package should be installed in its own sub-directory of /opt not at the top level. Users who want to run software in this directory may set their include and library paths approriately.
  For example MPICH resides in /opt/mpich-1.2.1/. A user who wanted to use MPICH would add /opt/mpich-1.2.1/bin to their PATH, etc.
  There should never be a directories such as lib, include or bin directly under /opt. If these directories exist, someone has screwed up.
• var
  This directory contains several interresting sub-directories:
  1. /var/log/
     contains the log files from a particular slave.
  2. /var/chroot/
     contains directories that hold chrooted file systems. At the moment this is used by BIND which runs chrooted in /var/chroot/bind/. Other programs that need to be run chrooted should have their root be placed in here
  3. /var/spool/mail
     is a symbolic link to /mnt/mail
  The other directories under /var are used by various operating system programs and should not be touched unless you know what you are doing.