Linux Learning Notes < 12 >--Disk Management

Device files:

B: Block files, Unit-by-block, randomly accessed devices, such as disks

C: Character file, in alphabetical order, to access linear devices, such as keyboards

Ls-l View the device files, the original display size of the column is changed to display as

Main device number (major numbers)

Used to identify the device type

Secondary device number (minor numbers)

Used to identify different devices of the same type

Mknod creating a block or character device file

Mknod [OPTION] ... NAME TYPE [MAJOR MINOR]

-M MODE Specify permissions

Example: Mknod-m 640 Mydev C 66 0

Device file name for the hard disk device:

Ide,ata:hd

Sata:sd

Scsi:sd

Usb:sd

A,b,c,... To differentiate different devices under the same type

Ide:

First IDE port: Master, slave

/dev/hda,/dev/hdb

Second IDE port: Master, slave

/DEV/HDC,/DEV/HDD

SDA, SDB, SDC, ...

Hda

HDA1: First primary partition

HDA2:

Hda3:

HDA4:

HDA5: First Extended partition

Check that the current system recognizes several hard drives:

fdisk-l [/dev/to/some_device_file]

Managing Disk Partitions

Fdisk/dev/sda

P: Displays the partition of the current hardware, including unsaved changes

N: Create a new partition

E: Extended partition

P: Primary partition

D: Delete a partition

W: Save exit

Q: Do not save exit

T: Modify the partition type

L: Show all supported types

Re-read partition table

Partprobe

File System Management

Cat/proc/filenames: Used to display the file systems supported by the current kernel

Mkfs:make filesystem Creating a file system

MKFS [OPTIONS] device files

-T Fstype

Mkfs-t ext2 = mkfs.ext2

Nkfs-t ext3 = Mkfs.ext3

Specialized in managing the Ext series file system

Mke2fs

-j: ext3 type of file system

-B block_size: Specify block size, default is 4096

-L LABEL: Specifies the partition volume label, with the volume label, you can use the volume label to refer to the partition, for example, using the label to mount

-M # (no plus%): Specifies the percentage of blocks reserved for super users, and-M 2 for reserved 2%

-I #: Creates an inode for the space specified as multibyte, defaults to 8192, and the value should be 2^n times the block size

-N #: Specify the number of Inode

-F: Force the file system to be created; The default file system is already mounted and cannot be recreated

-E: User-specified additional file system attributes, such as stride=# (Chunk/block_size), play a role for RAID0 and RAID5 and speed up operation

Blkid device files: Used to view related properties of disk devices, including UUID, type, and label

E2label: Used to view or define volume labels

E2label Device files: viewing volume labels

E2label device File Volume label name: Set Volume label

TUNE2FS: Modify file System related properties without reformatting, non-destructive modification

TUNE2FS [OPTION] device files

-j: Do not compromise the original data, upgrade the ext2 to ext3, but ext3 cannot downgrade to ext2

-L LABEL: Set or modify volume label

-M: Adjust the reserved percentage, use the same as MKE2FS, but do not reformat

-R: Directly sets the number of reserved blocks and cannot be used with-m

-C #: Specify the number of mounts to # times after the self-test, 0 or 1 means to turn off this feature

-I #: Specifies how many days to use after a self test without mounting, 0 or 1 for turning off this feature

-L: Show information in super fast

DUMPE2FS: Displays information from the Super block and information for each block group

DUMPE2FS [OPTION] device files

-H: Show only information in the Super block

Fsck: Checking and repairing the Linux file system

-T Fstype: Specifying the file system type

-A: Do not ask for automatic repair

E2FSCK: Designed to check and repair the Ext class file system

-F: Forced check

-P: Auto fix, default option

Mount/unmount File system

Mount: Associate a new file system to the current root file system

Uninstall: Remove the association of a file system from the current file system

Mount: Mount

Mount [option] [-o-option] device mount point

Equipment:

Device files

Volume Label: label= ""

Uuid:uuid= ""

mount point: Directory

Requirements:

1. Not used by other processes

2. The catalogue must exist beforehand

3. Files in the directory will be temporarily hidden, uninstall before they can be displayed again

: does not follow the parameters, display the current system has been changed to the device and mount point

-A: Indicates that all file systems in the/etc/fstab file are mounted

-N: By default, mount commands save the mounted device information to the/etc/mtab file, with the-n option not saved, for each device mounted

-T Fstype: Specifies the type of file system on which the device is being mounted, and when this option is not used, Mount automatically calls the Blkid command to obtain the type of the corresponding file system

-R: Read-only mount, which is often used for mounting discs

-W: Read-write Mount

-O: Specify additional mount options, that is, specify the properties of the file system startup

Remount: Re-mount without specifying mount point

RO: Read-only Mount

RW: Read-write Mount

Loop: Mount the local loopback device, mount the ISO image

When the mount is complete, the files on the corresponding file system are accessed via the mount point

Umount: Uninstalling a file system

Umount Equipment

Umount mount point

-N:

Mounting considerations: Mounted devices or mount points are not being used by the process

Fuser: Verifying the file or socket file that the process is using

-V: View running processes on a file

-KM: Terminates all processes that are accessing this directory

Fuser-km/path/to/directory

Create swap partition

Free: Displays memory and swap partitions, including total, used, free, etc.

-M: Default unit is KB, choose-m after unit changed to MB

Steps:

①fdisk command, N creates a partition

In the ②fdisk command, T adjusts the partition type to 82

③ Create swap partition:

1.mkswap Device files

-L LABEL

2.swapon device file: Enable swap partition

-A: Enable all switching devices defined in the/etc/fdtab file

3.swapoff device file: Turn off swap partition

Loopback devices:

Loopback, using software to simulate the implementation of hardware

DD: Create a specific file by specifying the data source and data storage destination

if= Data sources

of= Data storage target

bs=#: Block size, such as bs=1m

count=#: Number of blocks

seek=#: The size of skipped space when creating a data file

DD IF=/DEV/SDA of=/mnt/usb/mbr.backup bs=512 count=1 backup SDA MBR to U-disk

DD if=/mnt/usb/mbr.backup OF=/DEV/SDA bs=512 count=1 restore MBR

DD If/dev/zero of=/var/swapfile bs=1m count=1024 Create an empty file of 1G size

Mount ISO images, specific files, etc. with Mount

Mount-o Loop file path Mount_point

Mount-o Loop/var/swapfile/mnt/loopback1

Configuration file for FS/etc/fstab

The OS automatically mounts each file system defined in this file when it is initially

The format of each line:

Devices to mount:/dev/sda5

Mount point:/mnt/test

File system type: ext3

Mount option: Defaults

Switching frequency (make a full backup every few days): 0

File system detection order (only root can be 1): 0

Practice:

1, create a 5G partition, the file system is ext3, the volume label is MyData, the block size is 1024, the reserved management space for the disk partition 3%, requires the boot can automatically mount to the/data directory, and automatically mount the device to use the volume label for reference;

2, create a local loopback file/var/swaptemp/swapfile for swap, the size of 512MB, the volume labeled Swap-file, and power on automatically enable this switching device;

# mkdir/var/swaptemp

# dd If=/dev/zero of=/var/swaptemp/swapfile bs=1m count=512

# Mkswap Lable=swap-file/var/swaptemp/swapfile

Append in the/etc/fstab file

/var/swaptemp/swapfile swapswapdefaults0 0

3, the above first question, how to let it automatically mount the same time to enable the ACL function;

/etc/fstab

Label= ' MYDATA '/dataext3defaults,acl0 0

Linux Learning Notes < 12 >--Disk Management