Cloud DevOps Admin Guide

lsfs	Lists all filesystems in the /etc/filesystems entry
lsfs -a	To list all filesystems (default)
lsfs -q	List all filesystems with detailed info (shows size of FS and LV in it. so we can check whether size of LV=size os FS)
lsfs -l	Specify the output in list format
lsfs -c	Specify the output in column format
lsfs -v jfs	Lists all jfs filesystems
chfs -a size=24576 /test	Change size of FS /test to 24576(blocks)x 512 bytes  (12 MB)
chfs -a size=+24576 /test	Add 24576(blocks)x512 byte  to FS /test
chfs -a size=+64M /test	Add 64 MB to /test
chfs -a size=10G /test	fix size of the FS /test to 10 GB
chfs -m /test /new	Change the mount point from /test to /new
chfs -A /test	To auto mount the filesystem test
chfs -d account /test	Remove account attribute of /test.(from /etc/filesystems file)
chfs -a splitcopy=/backup -a copy=2 /oracle	This will mount the 2nd copy of mirrored filesystem oracle to /backup in read-only mode for backup purpose
crfs -v jfs2 -g newvg -a size=100M -m /test	Creates FS /test of type jfs in VG newvg of size 100 MB with default LV.
crfs -v jfs -d /dev/lv00 -m /test	Create FS /test of type jfs on device /dev/lv00
rmfs /test	Deletes FS /test and associated LV
rmfs -r /test	Deletes FS /test its mount point and associated LV
defragfs /test	To defragment the file system /test
defragfs -q /test	Display the current defrag status of the file system
fsck -y n /dev/lv00	To check the filesystem associated to /dev/lv00 assuming response "yes"
fsck -p /dev/lv00	To restore superblock from backup superblock

A filesystem is a logical collection of files on a partition or disk. A partition is a container for information and can span an entire hard drive if desired.
Everything in Unix is considered to be a file, including physical devices such as DVD-ROMs, USB devices, floppy drives, and so forth.
Unix uses a hierarchical file system structure, much like an upside-down tree, with root (/) at the base of the file system and all other directories spreading from there.
A UNIX filesystem is a collection of files and directories that has the following properties:

• It has a root directory (/) that contains other files and directories.
• Each file or directory is uniquely identified by its name, the directory in which it resides, and a unique identifier, typically called an inode.
• By convention, the root directory has an inode number of 2 and the lost+found directory has an inode number of 3. Inode numbers 0 and 1 are not used. File inode numbers can be seen by specifying the -i option to ls command.
• It is self contained. There are no dependencies between one filesystem and any other.

The directories have specific purposes and generally hold the same types of information for easily locating files. Following are the directories that exist on the major versions of Unix:

Directory	Description
/	This is the root directory which should contain only the directories needed at the top level of the file structure.
/bin	This is where the executable files are located. They are available to all user.
/dev	These are device drivers.
/etc	Supervisor directory commands, configuration files, disk configuration files, valid user lists, groups, ethernet, hosts, where to send critical messages.
/lib	Contains shared library files and sometimes other kernel-related files.
/boot	Contains files for booting the system.
/home	Contains the home directory for users and other accounts.
/mnt	Used to mount other temporary file systems, such as cdrom and floppy for the CD-ROM drive and floppy diskette drive, respectively
/proc	Contains all processes marked as a file by process number or other information that is dynamic to the system.
/tmp	Holds temporary files used between system boots
/usr	Used for miscellaneous purposes, or can be used by many users. Includes administrative commands, shared files, library files, and others
/var	Typically contains variable-length files such as log and print files and any other type of file that may contain a variable amount of data
/sbin	Contains binary (executable) files, usually for system administration. For example fdisk and ifconfig utlities.
/kernel	Contains kernel files