Device Management Common commands

Fdisk,sfdisk,part

Fdisk <= 15 partitions

fdisk-l [DEVICE]

fdisk [DEVICE]FDISK/DEV/SDA

Interactive commands:

D: Delete a partition

N: Create a new partition

P: Displays the current partition information

W: Save and exit

Q: Do not save exit

L: The system ID corresponding to each partition type;

83:linux

82:linux swap, swap partition

8e:lvm

Fd:soft Raid

T: Modify the system ID of the specified partition;

# cat/proc/partitions View the partition information identified by the kernel

Partprobe [DEVICE]: RHEL5 let kernel re-read hard disk partition table

partx-a [PARTITION] device:rhel6 allow kernel to reread hard disk partition table

Partx-a/DEV/SDA4/DEV/SDA

Next: Format the partition for creating the file system

LINUX,MKFS Formatting partitions

Mkfs-t fstyp/dev/partmkfs-t ext4/dev/sda4

Important: 1, the file system must be supported by the kernel to use, that is, the kernel has a corresponding kernel module, or has been integrated into the kernel

2, should have the corresponding file system creation tool, usually is mkfs,fstype

Rhel5:ext3

Rhel6:ext4

Mkfs-t Ext4 = MKFS.EXT4 = Mke2fs-t Ext4 =

Mkfs-t ext3 = Mkfs.ext3 = Mke2fs-j = Mke2fs-t ext3

Mkfs-t ext2 = mkfs.ext2 = MKE2FS = Mke2fs-t ext2

Profiles:/etc/mke2fs.conf, user-defined default features, and individual file system-specific features

mke2fs-t {EXT2|EXT3|EXT4}

-B {1024|2048|4096}: Block size

Block size depends on CPU support for memory page frame size, x86 system default Page box size is 4k

-L Label: Set Volume label

-M N: The proportion of the total space occupied by the block that is reserved for management use: n%

-R N: The number of blocks reserved for management use: N

-E: Setting extended properties of the file system

Tune2fs

-L: Display file system Super Block information tune2fs-l/dev/sda4

-L Label: re-set the volume label

-M N: Adjust the ratio of the total space occupied by the block reserved to the managed use: Change to n%

-R n: Adjust the number of blocks reserved for administration to use: N

-o: Set mount default option

-o: Set file system default features

-E: Adjusting extended properties of the file system

Tune2fs-l DEVICE | grep "Block Size": To display block sizes

E2abel: Displays or sets the volume label:

E2abel DEVICE [Volume_label]

Blkid device: Display the UUID and file system type

Mount Mount mounts [-t fstype] DEVICE Mount_point

-O: Used to specify mount options, common mount options

RO: Read-only Mount

RW: Read-write, read-write by default

Noatime: Turn off update access time

Auto: Can be mounted by "mount-a"

Defaults: equivalent to Rw,suid,dev,exec,auto,nouser,async,and relatime

Sync: Synchronous Write

Async: Asynchronous Write

Dev: Whether to allow the use of device files under this file system

Nodev

Remount: Re-mount

Loop: Local loopback device

-N: Do not update the/etc/mtab file when mounting the file system

-R: Equivalent to "-O ro", read-only Mount

Mount-o remount,other_options DEVICE

Mount-o loop,other_options device Mount_point for mounting loopback devices

Monut-t iso9660-o loop/root/centos-6.6-x86_64-bin-dvd1.iso/mnt/cdrom #把CentOS ... Mount to CDROM

Mount [-t Fstype] label= "Volume label" mount_point

Mount [-t Fstype] uuid= "UUID" Mount_point

# Mount #用这个命令会显示当前系统挂载的所有设备

Umount DEVICE

# UMOUNT/DEV/SDB3

Umount Mount_point

# Umount/media

After mounting, the original data will be hidden, so it can not be hung on the system common directory, will mount the uninstall, the original data will be displayed

When uninstalling, make sure no process is accessing the mounted device, otherwise it cannot be uninstalled

/etc/fstab: System will automatically mount the file system on boot

Fuser [Mount_point]: Viewing a process that is accessing a mount point

# fuser/media/

fuser-km [Mount_point]: Forcibly closes the process that is accessing this mount point

# fuser-km/media/

Swap partition for Linux: Swap

Must be a separate partition, separate file system

How big is the swap partition?

Scientific Computing Class Server: Swap memory can be as large as possible, such as twice times the physical memory

Application Class Server: Swap memory as small as possible, for example, only 1G

Physical memory is less than or equal to 2g,swap=memory*2

2G<MEMORY<4G, swap=memory*1.5

MEMORY>4G, swap=4g

How to view memory size:

Free Displays system usage and idle memory conditions, including physical memory, interactive area memory (swap), and kernel buffer memory

-M: Conversion of memory space size to MB

-G: Memory space size conversion to GB

gkfx: Shared memory

Buffer: Buffering

Cached: Caching

Mkswap DEVICE: Creating a Swap partition

-L label setting label

# mkwsap-l Newswap/dev/sda6

Swapon Enable swap partition:

Swapon DEVICE: Enable the specified swap partition

# Swapon/dev/sda6

SWAPON-A Enable all swap partitions

Swapoff DEVICE Disables swap partition

Swapoff-a

Auto enable swap partition on boot, can be defined in/etc/fstab

DEVICE swapswap defaults 0 0

mount point: Swap

File system type: Swap

DUMPE2FS: Output ext File System Information

-H: Show information about the super block

Du:disk usage

-s:summary, showing the sum of the sizes of all files under a specified path

-h:human-readable

Df:disk Free

-L: Show only information about the local file system

-H:

-p:posix-compatible style display

-I: Display inode usage information

New Hard disk

Creating partitions

Modify partition type T8e

Before you can create a physical volume pvcreate/dev/sdb{1,2}

Create Volume group vgcreate myvg/dev/sdb{1,2}

Create Logical Volume Lvcreate-l 10g-n mylv myvg-L Specify size-n Specifies the name of the logical volume

View the logical Volume LVS

Formatted mkfs.ext4-l mydata/dev/myvg/mylv

Lvm:logical Volume

PV: Physical Volume VG: Volume Group LV: Logical Volume

1. Logical Volume creation

PV-->VG-->LV

Pvcreare/dev/sdb5

Pvdisplay/dev/sdb5

PVs

Vgcreate VGNAME/DEV/SDB5 ...

-S PE

Vgdisplay

VGs

Lvcreate-l size-n-lv_name Vg_name

Number of-L PE

Lvdisplay

Lvs

Device files for logical volumes:/dev/vg_name/lv_name

/dev/mapper/vg_name-lv_name

/dev/mapper/testvg-mylv

2. Extended VG

First, prepare a PV.

Use the Vgextend command to complete the extension: Vgextend VG_NAME/PATH/TO/PV

3. Reduction of VG

Determine the PV to remove

Transfer data on this PV to other PV:PVMOVE/PATH/TO/PV

To remove this PV from the volume Group: Vgreduce VG_NAME/PATH/TO/PV

4. Extending the logical Volume

How big is the extension? 5G:-8G

Determine if the volume group that contains the current logical volume has enough free space:

Extensions:

1. Physical boundary: Lvextend-l [+]SIZE/PATH/TO/PV

2. Logical boundary: Resizefs/path/to/device

File System Detection:

fsck

e2fsck [-t fs_type] [-f] [-p]/path/to/device

5. Reduce the logical volume

How much are you sure to reduce? The premise is that you can at least accommodate all of the original data.

8G-3G

Reduction:

1, uninstall and forcibly detect the file system: E2fsck-f

2. Logical Boundary: Resize2fs/path/to/device SIZE

3. Physical boundary: Lvreduce-l [-]SIZE/PATH/TO/LV

6. Snapshot volume

Lvcreate

-S: Snapshot volume

-P R: Restrict snapshot volumes to read-only access

lvcreate-l size-s-P r-n lv_name/path/to/lv

7. Remove the logical Volume:

LVREMOVE/PATH/TO/LV

8. Remove the volume group

VGREMOVE/PATH/TO/VG

This article is from the "three elder brother" blog, please be sure to keep this source http://523958392.blog.51cto.com/9871195/1617632

Device Management Common commands