Create an LVM for the file system in centos 6.x

Create an LVM for the file system in centos 6.x

Partition

The most common partitioning tool in Linux is fdisk, which is easy to operate and use. However, a maximum of 15 partitioning tools can be used.

Fdisk-l view information about all disk partitions on the system.

Fdisk-l/dev/sd *

[Root @ www ~] # Fdisk-l/dev/sdb

Disk/dev/sdb: 21.5 GB, 21474836480 bytes

255 heads, 63 sectors/track, 2610 cylinders

Units = cylinders of 16065*512 = 8225280 bytes

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

I/O size (minimum/optimal): 512 bytes/512 bytes

Disk identifier: 0x07a95eb7

Device Boot Start End BlocksId System

Fdisk/dev/sd *

Several common parameters

D delete a partition

L list known partition types systemID corresponding to each partition type

N add a new partition create a new partition

P print the partition table print out the partition table is equivalent to fdisk-l/dev/sd *

Q quit without saving changes do not save current operation exit fdisk partition Tool

T change a partition's system id to change the system ID of a partition

W write table to disk and exit save current operation exit fdisk

Create an instance

[Root @ www ~] # Fdisk/dev/sdb partition/dev/sdb

WARNING: DOS-compatible mode is deprecated. It's stronugly recommended

Switch off the mode (command 'C') and change display units

Sectors (command 'U ').

Command (m for help): nn indicates creating a new partition.

Command action

E extended indicates the extended partition.

P primary partition (1-4) indicates the primary partition

P input batch to create a primary Partition

Partition number (1-4): 1. Enter the Partition number/dev/sdb1.

First cylinder (1-2610, default 1): Press enter to start from the First cylinder

Using default value 1

Last cylinder, + cylinders or + size {K, M, G} (1-2610, default 2610): + 5G partition size is 5 Gb. You can also enter the number of cylinders.

Command (m for help): p to view the partition information of the Disk

Disk/dev/sdb: 21.5 GB, 21474836480 bytes

255 heads, 63 sectors/track, 2610 cylinders

Units = cylinders of 16065*512 = 8225280 bytes

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

I/O size (minimum/optimal): 512 bytes/512 bytes

Disk identifier: 0x07a95eb7

Device name start cylindrical end cylindrical block size system Id type

Device Boot Start End BlocksId System

/Dev/sdb1 1 6545253223 + 83 Linux

Command (m for help): w save and exit

Thepartition table has been altered!

Callingioctl () to re-read partition table.

Syncingdisks.

Check whether partition operations are written to the system kernel

[Root @ www ~] # Cat/proc/partitions

Major minor # blocks name

8, 0, 26214400, sda

8 1 512000 sda1

8 2 25701376 sda2

816 20971520 sdb

817 5253223 sdb1

When the kernel cannot read the partition table on the hard disk, run the following command to run the partx command:

[Root @ www ~] # Partx-a/dev/sdb1/dev/sdb

To create a file system, use mkfsmkfs. ext [2 | 3 | 4] and mke2fs to create a file system. Generally, use mke2fs.

Mkfs-t ext2 = mkfs. ext2 = mke2fs-t ext2

Mkfs-t ext3 = mkfs. ext3 = mke2fs-t ext3

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

Mke2fs

Mke2fs-t type Device: What type of file system is created

Mke2fs-B {1024 | 2048 | 4096} block size of the Device Partition

[Root @ www ~] # Mke2fs-text4-B 2048/dev/sdc2

Mke2fs 1.41.12 (17-May-2010)

Filesystem label =

OS type: Linux

Block size = 2048 (log = 1)

Fragment size = 2048 (log = 1)

Stride = 0 blocks, Stripe width = 0 blocks

197880 inodes, 1578386 blocks

78919 blocks (5.00%) reserved for the superuser

First data block = 0

Maximum filesystem blocks = 538968064

97 block groups

16384 blocks per group, 16384 fragments pergroup

2040 inodes per group

Superblock backups stored on blocks:

16384,49152, 81920,114 688, 147456,409 600, 442368,802 816, 1327104

Writing inode tables: done

Creating journal (32768 blocks): done

Writing superblocks and filesystemaccounting information: done

This filesystem will be automaticallychecked every 24 mounts or

180 days, whichever comes first. Use tune2fs-c or-I to override.

[Root @ www ~] # Tune2fs-l/dev/sdc2 | grep "Block size"

Block size: 2048

[Root @ www ~] # Blkid/dev/sdc2

/Dev/sdc2: UUID = "ac40a50d-ddee-44b0-a6a8-481e7b33a548" TYPE = "ext4"

The default value for mke2fs creation is ext2.

[Root @ www ~] # Mke2fs/dev/sdb1

Mke2fs 1.41.12 (17-May-2010)

Filesystem label =

OS type: Linux

Block size = 4096 (log = 2)

Fragment size = 4096 (log = 2)

Stride = 0 blocks, Stripe width = 0 blocks

328656 inodes, 1313305 blocks

65665 blocks (5.00%) reserved for the superuser

First data block = 0

Maximum filesystem blocks = 1346371584

41 block groups

32768 blocks per group, 32768 fragments pergroup

8016 inodes per group

Superblock backups stored on blocks:

32768,98304, 163840,229 376, 294912,819, 884736

Writing inode tables: done

Writing superblocks and filesystemaccounting information: done

This filesystem will be automaticallychecked every 24 mounts or

180 days, whichever comes first. Use tune2fs-c or-I to override.

Mke2fs configuration file/etc/mke2fs. conf

[Defaults]

Base_features = sparse_super, filetype, resize_inode, dir_index, ext_attr ext2 File System by default

Blocksize = 4096 default block size

Inode_size = 256

Inode_ratio = 16384

Add the following features values to the default partition file system after base_features: ext3 or ext4.

[Fs_types]

Ext3 = {

Features = has_journal

}

Ext4 = {

Features = has_journal, extent, huge_file, flex_bg, uninit_bg, dir_nlink, extra_isize

Inode_size = 256

{

Tune2fs-l [DEVICE] has rich information displayed.

View the block size

[Root @ www ~] # Tune2fs-l/dev/sdb1 | grep "Block size"

Block size: 4096

Run the blkid command to view the UUID and file system type.

[Root @ www ~] # Blkid/dev/sdb1

/Dev/sdb1: UUID = "8595c196-9c41-4bfb-8b76-4930705e6c12" TYPE = "ext2"

Mount a File System

Mount-t type Device mount point

Mount command to view the file system mounted by the current system

[Root @ www ~] # Mount

/Dev/mapper/vg_centos-lv_root on/typeext4 (rw)

Proc on/proc type proc (rw)

Sysfs on/sys type sysfs (rw)

Devpts on/dev/pts type devpts (rw, gid = 5, mode = 620)

Tmpfs on/dev/shm type tmpfs (rw)

/Dev/sda1 on/boot type ext4 (rw)

None on/proc/sys/fs/binfmt_misc typebinfmt_misc (rw)

Sunrpc on/var/lib/nfs/rpc_pipefs typerpc_pipefs (rw)

Nfsd on/proc/fs/nfsd type nfsd (rw)

The/etc/mtab file can also be used to view the mounting status of the current system. The result of the mount command is from this file.

[Root @ www ~] # Cat/etc/mtab

/Dev/mapper/vg_centos-lv_root/ext4 rw 0 0

Proc/proc rw 0 0

Sysfs/sys sysfs rw 0 0

Devpts/dev/pts devpts rw, gid = 5, mode = 620 00

Tmpfs/dev/shm tmpfs rw 0 0

/Dev/sda1/boot ext4 rw 0 0

None/proc/sys/fs/binfmt_misc binfmt_miscrw 0 0

Sunrpc/var/lib/nfs/rpc_pipefs rpc_pipefsrw 0 0

Nfsd/proc/fs/nfsd rw 0 0

The mount command is valid at the time of mounting. If the system restarts, the file system to be mounted will be sucked into the/etc/fstab file.

LVM

LVM is a Logical volume management Logical VolumeManager. It manages disk partitions in Linux. LVM is a Logical layer built on hard disks and partitions, to improve the flexibility of disk partition management

The LVM creation sequence is PV --> VG --> LV. You do not know whether the default LVM is used when CentOS is installed by default.

Preparations before creation

Change the system ID of the partition to 8e (Linux LVM)

[Root @ www ~] # Fdisk/dev/sdc

Command (m for help): t

Partition number (1-4): 2

Hex code (type L to list codes): 8e

Changed system type of partition 2 to 8e (Linux LVM)

Command (m for help): p

Disk/dev/sdc: 21.5 GB, 21474836480 bytes

255 heads, 63 sectors/track, 2610 cylinders

Units = cylinders of 16065*512 = 8225280 bytes

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

I/O size (minimum/optimal): 512 bytes/512 bytes

Disk identifier: 0xbeaf1b91

Device Boot Start End BlocksId System

/Dev/sdc1 1 6545253223 + 83 Linux

/Dev/sdc2 655 10473156772 + 8e Linux LVM

LVM creation process

1. Pvcreate Device

[Root @ www ~] # Pvcreate/dev/sdc2

Physical volume "/dev/sdc2" successfully created

[Root @ www ~] # Pvcreate/dev/sdb1

Physical volume "/dev/sdb1" successfully created

2. [root @ www ~] # Vgcreate testvg/dev/sdb1/dev/sdc2

Volume group "testvg" successfully created

3. [root @ www ~] # Lvcreate-L 5G-ntestlv testvg

Logical volume "testlv" created

Verify that the lv has not been created

[Root @ www ~] # Lvdisplay/dev/testvg/testlv

--- Logical volume ---

LVPath/dev/testvg/testlv

LV Nametestlv

VG Name testvg

LVUUID UiuqXG-22fG-qKoz-dFzw-oHvP-OZYY-aOII0F

LVWrite Access read/write

LVCreation host, time www.linux.com, 20:21:14 + 0800

LVStatus available

# Open 0

LVSize 5.00 GiB

Current LE 1280

Segments 1

Allocation inherit

Read ahead sectors auto

-Currently sets to 256

Block device 253: 2

Create a File System

[Root @ www ~] # Mke2fs-text4/dev/testvg/testlv

Mount a File System

1. [Root @ www ~] # Mount-t ext4/dev/testvg/testlv/mnt

2. [Root @ www ~] # Mount

/Dev/mapper/vg_centos-lv_rooton/type ext4 (rw)

Procon/proc type proc (rw)

Sysfson/sys type sysfs (rw)

Devptson/dev/pts type devpts (rw, gid = 5, mode = 620)

Tmpfson/dev/shm type tmpfs (rw)

/Dev/sda1on/boot type ext4 (rw)

Noneon/proc/sys/fs/binfmt_misc type binfmt_misc (rw)

Sunrpcon/var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)

Nfsdon/proc/fs/nfsd type nfsd (rw)

Gvfs-fuse-daemonon/root/. gvfs type fuse. gvfs-fuse-daemon (rw, nosuid, nodev)

/Dev/sr0on/media/CentOS_6.4_Final type iso9660 (ro, nosuid, nodev, uhelper = udisks, uid = 0, gid = 0, iocharset = utf8, mode = 0400, dmode = 0500)

/Dev/mapper/testvg-testlvon/mnt type ext4 (rw)

LVM Usage Details vg

1. Vg volume group Expansion

Prepare a pv

[Root @ www ~] # Pvcreate/dev/sdb2

Physical volume "/dev/sdb2" successfully created

Expand the capacity of vg

Run vgextend command vgextend vgname Device

[Root @ www ~] # Vgextendtestvg/dev/sdb2

Volume group "testvg" successfully extended

[Root @ www ~] # Vgs

Couldn't find device with uuid 2QpQ6S-B9Oz-7PB1-fIKo-Lhdw-h00t-3EtX00.

VG # PV # LV # SN Attr VSizeVFree

VG 2 0 0wz-pn-8.02g 8.02g

Testvg 31 0 wz -- n-15.02g 10.02g

Vg_centos 1 2 0wz -- n-24.51g 0

2. vg volume group reduction

Move the data on the pv to another pv.

[Root @ www ~] # Pvmove/dev/sdb1

/Dev/sdb1: Moved: 0.1%

/Dev/sdb1: Moved: 64.8%

/Dev/sdb1: Moved: 100.0%

Vgreduce command to reduce vg vgreduce vgname Device

[Root @ www ~] # Vgreducetestvg/dev/sdb1

Removed "/dev/sdb1" from volume group "testvg"

3. Delete the vg volume group

[Root @ www ~] # Vgremove testvg

Volume group "testvg" successfully removed

Lv

Lv Extension

First, check whether the volume group of the lv is in sufficient space.

1. Expand physical boundaries

[Root @ www ~] # Lvextend-L + 2G/dev/testvg/testlv

Extending logical volume testlv to 7.00 GiB

Logical volume testlv successfully resized

2. Extend logical boundaries

[Root @ www ~] # Resize2fs/dev/testvg/testlv

Resize2fs 1.41.12 (17-May-2010)

Filesystem at/dev/testvg/testlv is mountedon/mnt; on-line resizing required

Old desc_blocks = 1, new_desc_blocks = 1

Ming an on-line resize of/dev/testvg/testlv to 1835008 (4 k) blocks.

The filesystem on/dev/testvg/testlv is now1835008 blocks long.

3. Check that the lv extension is successful.

[Root @ www ~] # Df-lh

Filesystem Size Used Avail Use % Mounted on

/Dev/mapper/vg_centos-lv_root

23G 17G4. 2G 81%/

Tmpfs 935M0 935 M 0%/dev/shm

/Dev/sda1 485 M 47M414M 11%/boot

/Dev/mapper/testvg-testlv

6.9G 140M6. 5G 3%/mnt

Lv reduction

Before reducing the lv, you must uninstall it and forcibly detect the file system.

[Root @ www ~] # Umount/dev/testvg/testlv

[Root @ www ~] # Fsck-f/dev/testvg/testlvfsck is a file system detection tool. The-f parameter is added to indicate forced detection.

Fsck from util-linux-ng 2.17.2

E2fsck 1.41.12 (17-May-2010)

Pass 1: Checking inodes, blocks, and sizes

Pass 2: Checking directory structure

Pass 3: Checking directory connectivity

Pass 4: Checking reference counts

Pass 5: Checking group summary information

/Dev/mapper/testvg-testlv: 12/458752 files (0.0% non-contiguous), 64448/1835008 blocks

If the file system is not detected, garbled characters may occur during future use.

1. Reduce logical volume

Resizefs Device size

[Root @ www ~] # Resize2fs/dev/testvg/testlv 5G

Resize2fs 1.41.12 (17-May-2010)

Resizing the filesystem on/dev/testvg/testlv to 1310720 (4 k) blocks.

2. Reduce physical volumes

[Root @ www ~] # Lvreduce-L5G/dev/testvg/testlv

WARNING: switching active logical volume to 5.00 GiB

This may destroy your data (filesystem etc .)

Do you really want to reduce testlv? [Y/n]: y

Cing logical volume testlv to 5.00 GiB

Logical volume testlv successfully resized

3. Remove the lv volume

A) uninstall the lv volume mount

B) Use lvremove Device to remove the lv volume

[Root @ www ~] # Umount/mnt

[Root @ www ~] # Lvremove/dev/testvg/testlv

Do you really want toremove active logical volume testlv? [Y/n]: y

Logical volume "testlv" successfully removed

Verify

[Root @ www ~] # Lvs

Couldn't find device with uuid 2QpQ6S-B9Oz-7PB1-fIKo-Lhdw-h00t-3EtX00.

Lv vg Attr LSizePool Origin Data % Move LogCpy % Sync Convert

Lv_root vg_centos-wi-ao --- 22.57g

Lv_swap vg_centos-wi-ao --- 1.94g

Note:

Lvreduce-L [+ |-] size Device indicates how much space is added or reduced on the basis of the original volume size.

Lvreduce-L size Device indicates how much space the original volume is directly extended.

The LVM cut sequence is LV --> VG --> PV.

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