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Partition and management of disk

This paper introduces the operation commands related to disk partition and management in linux system, and tests are added to each main command.

1. Disk partition: fdisk

Here we mainly use traditional disk partitions, not involving mdm, lvm and so on.

1. To view disk partition information, using fdisk-l, you can view information about traditional disk partitions and lvm volumes.

[root@liuqing ~] # fdisk-l

Disk / dev/sda:128.8 GB, 128849018880 bytes, 251658240 sectors

Units = sector of 1 * 512 = 512 bytes

Sector size (logical / physical): 512 bytes / 512 bytes

Igamo size (minimum / best): 512 bytes / 512 bytes

Disk label type: dos

Disk identifier: 0x000ce7f5

Device Boot Start End Blocks Id System

/ dev/sda1 * 2048 2099199 1048576 83 Linux

/ dev/sda2 2099200 209715199 103808000 8e Linux LVM

Disk / dev/mapper/centos-root:53.7 GB, 53687091200 bytes, 104857600 sectors

Units = sector of 1 * 512 = 512 bytes

Sector size (logical / physical): 512 bytes / 512 bytes

Igamo size (minimum / best): 512 bytes / 512 bytes

Disk / dev/mapper/centos-swap:2147 MB, 2147483648 bytes, 4194304 sectors

Units = sector of 1 * 512 = 512 bytes

Sector size (logical / physical): 512 bytes / 512 bytes

Igamo size (minimum / best): 512 bytes / 512 bytes

Disk / dev/mapper/centos-home:50.5 GB, 50457477120 bytes, 98549760 sectors

Units = sector of 1 * 512 = 512 bytes

Sector size (logical / physical): 512 bytes / 512 bytes

Igamo size (minimum / best): 512 bytes / 512 bytes

2. Main parameters of fdisk

Note: fdisk operates in memory and does not operate on disk in real time. It is written to disk only when you save the disk using the w command.

D delete a partition # Delete a partition

L list known partition types # shows known partition types, common 82, 83, 8e,

M print this menu # displays the command menu

N add a new partition # create a new partition

P print the partition table # displays the partition table

Q quit without saving changes # do not save exit

T change a partition's system id # adjust partition type

W write table to disk and exit # Save and exit

3. Lab: create a 10G partition with partition type 83 and partition number / dev/sda3

[root@liuqing ~] # fdisk-l / dev/sda

Command (enter m for help): n

Partition type:

P primary (2 primary, 0 extended, 2 free)

E extended

Select (default p): P

Area number (3pd4, default 3): 3

Start sector (209715200-251658239, default is 209715200):

The default value of 209715200 will be used

Last sector, + sector or + size {K Magne M Magi G} (209715200-251658239, default is 251658239): + 10G

Partition 3 has been set to type Linux and the size is set to 10 GiB

Command (enter m for help): W

The partition table has been altered!

Calling ioctl () to re-read partition table.

# when creating a partition, enter the command n

# then choose whether the type of partition is primary partition or extended partition. For MBR disks, there are up to 4 primary partitions plus extended partitions

# Select partition number 1-4 as the primary partition or extended partition, and the logical partition under the extended partition starts from 5

# enter the starting sector number and partition size

# save and exit

4. Check the partition information, there is already one more.

[root@liuqing ~] # fdisk-l

Device Boot Start End Blocks Id System

/ dev/sda1 * 2048 2099199 1048576 83 Linux

/ dev/sda2 2099200 209715199 103808000 8e Linux LVM

/ dev/sda3 209715200 230686719 10485760 83 Linux

Second, let the kernel read the disk

After creating a partition using fdisk, the kernel does not recognize it in real time, and you need to use the command to reread the partition. There are two commands used: partx and kpartx.

1. Look at the partition information that has been recognized by the kernel and do not see the / dev/sda3 information.

[root@liuqing ~] # cat / proc/partitions

Major minor # blocks name

8 0 125829120 sda

8 1 1048576 sda1

8 2 103808000 sda2

. Omit other irrelevant information

two。 Use partx to reread the partition information, and if it doesn't work once, you can do it again.

[root@liuqing] # partx-a / dev/sda

Partx: / dev/sda: error adding partitions 1-2

[root@liuqing ~] # cat / proc/partitions

Major minor # blocks name

8 0 125829120 sda

8 1 1048576 sda1

8 2 103808000 sda2

8 3 10485760 sda3

3. How to use partx and kpartx

A. partx-a [device]

B. kpartx-af [device]

Third, create a file system

Master the commands and parameters for creating a file system

Here we mainly introduce the use of ext series file system creation tool mke2fs, which is more powerful. Other commands include mkfs.ext2, mkfs.ext3, mkfs.ext4; mkfs, etc.

Mke2fs [OPTIONS] device

-t {ext2 | ext3 | ext4}: indicates the type of file system to be created

Mkfs.ext4 = mkfs-t ext4 = mke2fs-t ext4

-b {1024 | 2048 | 4096}: indicates the block size of the file system

-L LABEL: indicates the volume label

-j: create a journaling file system ext3

Mke2fs-j = mke2fs-t ext3 = mkfs-t ext3 = mkfs.ext3

-I #: bytes-per-inode, indicating the ratio of inode to bytes; that is, creating an Indode for every number of bytes

-N #: directly indicates the number of inode to be created for this file system

-m #: specify reserved space, percentage

-O [^] FEATURE: creates the target file system with the specified properties

Lab: create a file system for / dev/sda3, the file system type is ext4, the block size used by the system is 2048, the volume label is Mydata, and the space reserved for the administrator is 4%

[root@liuqing] # mke2fs-t ext4-b 2048-L "Mydata"-M4 / dev/sda3

Mke2fs 1.42.9 (28-Dec-2013)

File system label = Mydata

OS type: Linux

Block size = 2048 (log=1)

Chunk size = 2048 (log=1)

Stride=0 blocks, Stripe width=0 blocks

655360 inodes, 5242880 blocks

209715 blocks (4.00%) reserved for the super user

First data block = 0

Maximum filesystem blocks=273678336

320 block groups

16384 blocks per group, 16384 fragments per group

2048 inodes per group

Superblock backups stored on blocks:

16384, 49152, 81920, 114688, 147456, 409600, 442368, 802816, 1327104

2048000, 3981312

Allocating group tables: done

Writing inode table: complete

Creating journal (32768 blocks): complete

Writing superblocks and filesystem accounting information: done

Adjust partition properties and other commands

1. E2label: used to view and set volume labels

Viewing: e2label DEVICE

Settings: e2label DEVICE LABEL_NAME

2. Dumpe2fs: used to display attribute information of ext series file systems

Dumpe2fs [- h] device

3. E2fsck: disk check for ext series file systems

E2fsck [OPTIONS] device

-y: automatically answer yes to all questions

-f: force detection even if the file system is in the clean state

4. Fsck:check and repair a Linux file system

-t fstype: indicates the file system type

Fsck-t ext4 = fsck.ext4

-a: automatically fix all errors without interaction

-r: interactive repair

5. Tune2fs

Tune2fs command: view or modify some properties of the ext series file system

Adjust tunable filesystem parameters on ext2/ext3/ext4 filesystems

Note: the block size cannot be modified after it is created

Tune2fs [OPTIONS] device

-l: view the contents of the super block

Modify the properties of the specified file system:

-j:ext2-- > ext3

-L LABEL: modify the volume label

-m #: adjust the percentage of reserved space

-O [^] FEATHER: turn a feature on or off

-o [^] mount_options: turns some default mount option on or off

Acl

^ acl

6. View information about partition super blocks

[root@liuqing ~] # tune2fs-l / dev/sda3

Tune2fs 1.42.9 (28-Dec-2013)

Filesystem volume name: Mydata

Last mounted on:

Filesystem UUID: 63a8e0d5-27b4-4dd6-9049-3f11acb620b7

Filesystem magic number: 0xEF53

Filesystem revision #: 1 (dynamic)

Filesystem features: has_journal ext_attr resize_inode dir_index filetype extent 64bit flex_bg sparse_super huge_file uninit_bg dir_nlink extra_isize

Filesystem flags: signed_directory_hash

Default mount options: user_xattr acl

Filesystem state: clean

Errors behavior: Continue

Filesystem OS type: Linux

Inode count: 655360

Block count: 5242880

Reserved block count: 209715

Free blocks: 5121266

Free inodes: 655349

First block: 0

Block size: 2048

Fragment size: 2048

Group descriptor size: 64

Reserved GDT blocks: 512

Blocks per group: 16384

Fragments per group: 16384

Inodes per group: 2048

Inode blocks per group: 256

Flex block group size: 16

Filesystem created: Thu Nov 28 11:12:37 2019

Last mount time: n/a

Last write time: Thu Nov 28 11:12:38 2019

Mount count: 0

Maximum mount count:-1

Last checked: Thu Nov 28 11:12:37 2019

Check interval: 0 ()

Lifetime writes: 65 MB

Reserved blocks uid: 0 (user root)

Reserved blocks gid: 0 (group root)

First inode: 11

Inode size: 256

Required extra isize: 28

Desired extra isize: 28

Journal inode: 8

Default directory hash: half_md4

Directory Hash Seed: e2e55f5f-e05f-431c-84b9-a734d29b078f

Journal backup: inode blocks

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