Thursday, January 12, 2012

Managing the Solaris File System Root Subdirectories

I have provided a list below to explain how Solaris manages their Root file system.

Critical Directories:
Directory Description
/ The root of the overall file system namespace.
/bin A symbolic link to the /usr/bin directory.  It is the directory location for the binary files of standard system commands.
/dev The primary directory for logical device names.  The contents of this directory are symbolic links that point to device files in the /devices directory.
/etc The directory that holds host-specific configuration files and databases for system administration.
/export The default directory for commonly shared file systems, such as users' home directories, application software, or other shared file systems.
/home The default directory or mount point for a user's home directory.
/kernel The directory of platform-independent loadable kernel modules that are required as part of the boot process.
/lib The contents of this directory are shared executable files and Service Management Facility executables.
/mnt A convenient, temporary mount point for file systems.
/opt The default directory or mount point for add-on application packages.
/platform The directory of platform-dependent loadable kernel modules.
/sbin The single-user bin directory that contains essential executables that are used during the booting process and in manual systemfailure recovery.
/usr The directory that contains programs, scripts, and libraries that are used by all system users.
/var The directory for varying files, which usually includes temporary, logging, or status files.

Following the introduction of the Service Management Facility and Zones, in the Solaris 10 OS, the /var directory hierarchy is more heavily used than in previous releases.

It is important that the /var directory has sufficient disk space available to store software package information, log files, spool files, and so on.

In-Memory System Directories:
Directory Description
/dev/fd The directory that contains special files relating to current file-descriptors in use by the system.
/devices The primary directory for physical device names.
/etc/mnttab A memory-based file, in its own file system, that contains details of current file system mounts.
/etc/svc/volatile The directory that contains log files and reference files relating to the current state of system services.
/proc The directory that stores current process-related information. Every process has its own set of subdirectories below the /proc directory.
/system/contract CTFS (the contract file system) is the interface for creating, controlling, and observing contracts. A contract enhances the relationship between a process and the system resources it depends on by providing richer error reporting and (optionally) a means of delaying the removal of a resource.

The service management facility (SMF) uses process contracts to track the processes which compose a service, so that a failure in a part of a multi-process service can be identified as a failure of that service.

The contract file system supports all the SMF services.
/system/object The OBJFS (object) file system describes the state of all modules currently loaded by the kernel. This file system is used by debuggers to access information about kernel symbols without having to access the kernel directly. It is used primarily for Dtrace activity.
/tmp The directory for temporary files. This directory is cleared during the boot sequence.
/var/run The directory that contains lock files, special files, and reference files for a variety of system processes and services.

Note: These in-memory directories are maintained by the kernel and system services. Users should never attempt to manually create, alter, or remove files from these directories.

Primary Subdirectories Under the /dev Directory
Directory Description
/dev/dsk Block disk devices
/dev/fd File descriptors
/dev/md Logical volume management metadisk devices
/dev/pts Pseudo terminal devices
/dev/rdsk Raw disk devices
/dev/rmt Raw magnetic tape devices
/dev/term Serial devices

Primary Subdirectories Under the /etc Directory:
Directory Description
/etc/acct Configuration information for the accounting system
/etc/cron.d Configuration information for the cron utility
/etc/default Default information for various programs
/etc/inet Configuration files for network services
/etc/init.d Scripts for starting and stopping services
/etc/lib Dynamic linking libraries needed when the /usr file system is not available
/etc/lp Configuration information for the printer subsystem
/etc/mail Configuration information for the mail subsystem
/etc/nfs Configuration file for NFS server logging
/etc/opt Configuration information for optional packages
/etc/rc#.d Legacy scripts that are executed when entering or leaving a specific run level
/etc/security Control files for Role Based Access Control and security privileges
/etc/skel Default shell initialization files for new user accounts
/etc/svc The Service Management Facility database and log files
/etc/zones Initialization and reference files for the Solaris 10 OS Zones facility

Contents of the /usr Directory:
Directory Description
/usr/bin Standard system commands
/usr/ccs C-compilation programs and libraries
/usr/demo Demonstration programs and data
/usr/dt Directory or mount point for Common Desktop Environment (CDE) software
/usr/include Header files (for C programs, and so on)
/usr/jdk Directories that contain Java technology programs and libraries
/usr/kernel Platform-independent loadable kernel modules that are not generally required during the boot process
/usr/lib Architecture-dependent databases, various program libraries, and binaries that are not invoked directly by the user
/usr/opt Configuration information for optional packages
/usr/sbin System administration commands
/usr/spool Symbolic link to the /var/spool directory

Primary Subdirectories Under the /var Directory:
Directory Description
/var/adm Log files (for syslog, system accounting, and so on).
/var/crash For storing crash dump files following a catastrophic system failure. Files from this directory can be analyzed by Help Desk staff to determine the cause of the system crash.
/var/spool Spooled files (for mail, print services, and so on).
/var/svc Service Management Facility control files and logs.
/var/tmp Long-term storage of temporary files across a system reboot, as an alternative to the /tmp directory.

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