4.1 create partitions and filesystems

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System Administration

Key Knowledge Areas
ext2
Ext3-4
xfs
reiserfs v3
vfat
Devices, Linux Filesystems, Filesystem Hierarchy Standard
Create partitions and filesystems
Terms and Utilities
fdisk
mkfs
mkswap
2

File Systems
3
FILE SYSTEM
is the methods and data structures that an operating system uses to keep track of files on disk or partition
or, the way the files are organized on disk
Linux Filesystems can be created with the mkfs command.
Cmd is a front end to several filesystem-specific commands (such as mkfs.ext3 for ext3 and mkfs.reiserfs for ReiserFS)
To view what filesystem-specific support is installed on the system use: ls /sbin/mk* command.
Linux Swapspaces are created with the mkswap command.
Ex: yourname@yourcomp~> ls /sbin/mk*
/sbin/mkdosfs /sbin/mkfs.ext2 /sbin/mkfs.ntfs
/sbin/mke2fs /sbin/mkfs.ext3 /sbin/mkfs.vfat
/sbin/mkfs /sbin/mkfs.ext4 /sbin/mkfs.xfs
/sbin/mkfs.btrfs /sbin/mkfs.ext4dev /sbin/mkhomedir_helper
/sbin/mkfs.cramfs /sbin/mkfs.msdos /sbin/mkswap

File Systems
4
Linux Swapspaces and Filesystems can be created with fdisk
Ex: yourname@yourcomp~> fdisk -v
fdisk (util-linux-ng 2.16)
yourname@yourcomp~> sudo fdisk /dev/sdb
[sudo] password for:
The number of cylinders for this disk is set to 30401.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
(e.g., DOS FDISK, OS/2 FDISK)
Command (m for help): p
Disk /dev/sdb: 250.1 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x000404d6
Device Boot Start End Blocks Id System
/dev/sdb1 1 25 200781 83 Linux
/dev/sdb2 26 12965 103940550 83 Linux
/dev/sdb3 12966 30401 140054670 83 Linux
Command (m for help):

Creating a swap space
5
swap space from other partition with mkswap
Ex: yourname@yourcomp~> mkswap /dev/sda4
Setting up swapspace version 1, size = 4192960 KiB
no label, UUID=8f5a3a05-73ef-4c78-bc56-0e9b1bcc7fdb
mkswap doesnt check if file or partition isn't used.
It can overwrite important files and partitions
swap space is part of hard disk that is used as virtual memory
Linux can use a normal file in filesystem or separate partition for swap space.
used as a raw partition, and will not contain any filesystem. type 82 (Linux swap);

6
Ex: yourname@yourcomp~> dd if=/dev/zero of=/extra-swap bs=1024
count=1024
1024+0 records in
1024+0 records out
/extra-swap is the name of the swap file and the size of is given after the count=.
yourname@yourcomp~> mkswap /extra-swap 1024
Setting up swapspace, size = 1044480 bytes
After created a swap file or swap partition, you need to write a signature to its beginning;
contains administrative information used by kernel. command to do is mkswap
Ex:
the swap space is still not in use: it will exist, but the kernel does not use it to provide virtual memory.

7
initialized swap space is used with swapon.
tells kernel that swap space can be used and path to swap space is given as argument
Ex:
yourname@yourcomp~> swapon /extra-swap
to start swapping on temporary swap file use the following command:
/dev/hda8 none swap sw 0 0
/swapfile none swap sw 0 0
startup scripts will run command swapon -a, which will start swapping on all the swap spaces listed in /etc/fstab
Ex:
Swap spaces can be used automatically by listing them in /etc/fstab file
swap space can be removed with swapoff
swap used automatically with swapon -a can be removed from with swapoff -a; it looks at /etc/fstab to find what to
remove

8
monitor swap with free or top or in /proc/meminfo
View enabled swap devices use swapon –s or with cat /proc/swaps
yourname@yourcomp~> swapon –s
Filename Type Size Used Priority
/dev/sdb1 partition 514044 0 -1
yourname@yourcomp~> cat /proc/swaps
Filename Type Size Used Priority
Ex:

Creating an ext3 filesystem
9
Ex: yourname@yourcomp~> mkfs -t ext3 /dev/sda8
mke2fs 1.41.9 (22-Aug-2009)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
2624496 inodes, 10488429 blocks
524421 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
321 block groups
32768 blocks per group, 32768 fragments per group
8176 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
4096000, 7962624
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 20 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
• To add journal to an existing ext2, use tune2fs with -j option.
• To display or set label for ext2 or ext3, use e2label. Labels limited to 16 characters.
• To display UUID (Universally Unique Identifier) for the formatted partition, use blkid cmd
Linux filesystems generate UUID when the filesystem is formatted - 128-bit identifier displayed as 32 hexadecimal digit and four
hyphens

Other tools and filesystems
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cfdisk tool (console based)
Ex:

Other tools and filesystems
11
gpart partitioning tool
Ex:

Linux file system
12
Linux filesystem contains files arranged on a block storage device in directories.
Linux filesystem is a single tree with the / directory as its root directory.
Ex:

File system Hierarchy Standard
13
Directories required in / by the Filesystem Hierarchy Standard
Set of requirements and guidelines for file and directory placement under UNIX-like operating systems.
Directory Description
bin Essential command binaries
boot Static files of the boot loader
dev Device files
etc Host-specific system configuration
lib Essential shared libraries and kernel modules
media Mount point for removable media
mnt Mount point for mounting a filesystem temporarily
opt Add-on application software packages
sbin Essential system binaries
srv Data for services provided by this system
tmp Temporary files
usr Secondary hierarchy
var Variable data
http://www.pathname.com/fhs/

Filesystem Hierarchy Standard
14
Ex:

Linux file system
15
A simple description of UNIX system, applicable to Linux, is:
"On a UNIX system, everything is a file; if something is not a file, it is a process.”
• Regular files: Contain normal data. Ex. text files, executable files or progs, input for or output from a program.
• Directories: Files that are lists of other files.
• Special files: The mechanism used for input and output. Most special files are in /dev
• Links: System to make a file or directory visible in multiple parts of the system's file tree.
• Domain sockets: Special file type (similar to TCP/IP sockets) providing inter-process networking protected by the file
system's access control.
• Named pipes: More or less like sockets. Form a way for processes to communicate with each other, without using
network socket semantics.

Linux file system
16
The -l option to ls cmd displays the file type, using the first character of each input line
Good options are with -F and --color combined:
Ex: yourname@yourcomp~> ls -l
total 80
-rw-rw-r-- 1 jaime jaime 31744 Feb 21 17:56 intro Linux.doc
-rw-rw-r-- 1 jaime jaime 41472 Feb 21 17:56 Linux.doc
drwxrwxr-x 2 jaime jaime 4096 Feb 25 11:50 course
File types in ls -long list
Symbol Meaning
•- Regular file
•d Directory
•l Link
•c Special file
•s Socket
•p Named pipe
•b Block device
File types in ls –F
suffixes to non-standard file name. For mono-color use and printing
Character File type
•nothing Regular file
•/ Directory
•* Executable file
•@ Link
•= Socket
•| Named pipe
View info coreutils ls

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4.1 create partitions and filesystems

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4.1 create partitions and filesystems