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The physical volume is LVM The basic storage device of the mechanism , It usually corresponds to an ordinary partition or the whole disk . When creating a physical volume , A reserved partition will be created at the head of the partition or hard disk , Used to record LVM Properties of , And divide the storage space into the default size of 4MB The basic unit of . To form a physical volume , Physical volumes generally use the device file name directly , Such as /dev/sdb1./dev/sdb2./dev/sdd etc.

VG （ The volume group ）

An entity consisting of one or more physical volumes , Volume group , Dynamically add or remove physical volumes from each volume group . Many physical volumes can be grouped into different volume groups , The name of the volume group is user-defined .

LV（ Logic volume ）

Logical volumes are built on top of volume groups , Not directly related to physical volumes , Each volume group is a whole , Cut out a small space from the whole as the basis for users to create file systems , This small space is called logical volume usage .

Two , LVM Command management of

function	Physical volume management	Volume group management	Logical volume management
Scan scanning	pvscan	vgscan	lvscan
Create establish	pvcreate	vgcreate	lvcreate
Display Show	pvdisplay	vgdisplay	lvdisplay
Remove Delete	pvremove	vgremove	lvremove
Extend Expand		vgextend	lvextend
Reduce Reduce		vgreduce	lvreduce

pvcreate Equipment I Equipment II

vgcreate Volume group name Equipment I Equipment II

lvcreate -L Capacity size -n Logical volume name Volume group name

lvextend -L Capacity size /dev/ Volume group name / Logical volume name

technological process

1, Hard disk partition

fidsk dev/sdb      fdisk .dev/sdc

2, Create a physical volume

 Create a physical volume  sdb1,sdc1
pvcreate /dev/sdb1   /dev/sdc1

3, Create a volume group

vgcreate web_kgc /dev/sdb1  /dev/sdc1

4, Create logical partitions

lvcreate -L  Capacity size  -n  Logical volume name   Volume group name 
lvcreate -L +10G -n mail——store  web—kgc

5, Create file system

mkfs -t xfs /dev/web_kgc/nizb

6, Mount Directory

mount /dev/web_kgc/nizb/home

7, Permanently mount

echo "dev/web_kgc/nizb            /home    xfs     defaults    0 0 " >> etc/fstab

3、 ... and ,LVM Application example

Shut down and add two pieces 20G Of disks , be used for LVM Partition

Partition the disk , And change it to LVM Format .

Create a physical volume

Set up a volume group

Create logical volumes

pvdisplay Check the information

Create file system Format file

Mount

Expand logical volume space （ add to 5G）

Refresh xfs file system

df -hT Check whether it has been added

Four , Disk quota overview

1, What is disk quota , What is the use of disk quotas

When Linux When the root partition runs out of disk space ,Linux The operating system will no longer be able to create new files , At the same time, the service program may crash , Failure of system startup .

In order to avoid the problem of insufficient disk space in the server , The disk quota function can be enabled , For the user in the specified file system ( Partition ) Disk space used in 、 Limit the number of files , To prevent individual users from occupying a large amount of disk space maliciously or unintentionally , So as to maintain the stability and sustainability of the system storage space

stay cento8 In the system , Different file systems use different disk quota configuration management T have . for example ,XFS File system pass xfs__quota Tools to manage ;ExT3/4 The document is passed quotaT Tools for management .

2, Disk quota

Conditions for achieving disk quota

need Linux The kernel support

install xfsprogs and quota software package

Linux Characteristics of disk quota

Scope of action ： For the specified partition

Restricted objects ： The user account , Group account number

Type of restriction ： Disk capacity , Number of documents

Limiting method ： Soft limit , Hard limit

3, Characteristics of disk quota

1. The role of disk quotas xfs_quota

Set the disk quota function , Only on the specified file system （ Partition ) Effective within , When users use other file systems without quotas , There will be no restrictions .

2. disk f The quota t Restricted objects for xfs_quota

Mainly for the user account specified in the system 、 Group account restrictions , Users or groups without quotas will not be affected . After setting the quota for the group account , The base disk capacity used by all users in the Group 、 The total number of files cannot exceed the limit .

3. The restriction type of the disk

Disk capacity : Limit the disk data blocks that users can use （Elock) size , That is, limit the size of disk space , The default unit is KB Number of documents : Limit the number of files that users can have . stay Linux Operating system , Each file has a corresponding Suning mark . be called i node (Inode） Number , This number is unique in the same file system , therefore xfs_quota Pass restrictions i To limit the number of files .

4. How to limit disk quota

Soft limit : Specify a soft quota value, such as （ 480MB disk space 、180 File ）), During the grace period set by the week （ The default is seven days ） It is allowed to temporarily exceed this limit , But the system will give a warning message .

Hard limit : Specify a hard quota value （ Such as 500MB Disk room 、200 File ), Is the limit that users are absolutely forbidden to exceed , When the hard limit is reached , The system will also give a warning and prohibit further writing data . The quota value of hard limit should be greater than the corresponding soft limit value , Otherwise, the soft limit will fail .

As can be seen from the above description , In the actual process of implementing disk quotas , Only with ( Or group ）、 file system （ Partition ） And quota values meet the quota conditions , xfs_quota Will limit the operation

5, Start disk quota support

1 Start quota support for the file system

add to usrquota,grpquota Mount parameters

2, Edit quota settings for user and group accounts

Use xfs_quota Command to edit quota settings

[[email protected] /]# xfs_quota -x -c 'limit -u bsoft=40M bhard=80M isoft=8 ihard=10 jie' /saryn/

Common options

-x	Indicates start expert mode , In the current mode, it is allowed to modify the quota system, so the management commands are available
-c	Means to directly call the management command
-u	Specify user account and object
-g	Specify the group account object

Limit field

bsoft	Set the soft limit value of disk capacity （ The default is KB）
bhard	Set the hard limit value of disk capacity （ The default is KB）
isoft	Set the soft limit value for the number of disk files
ihard	Set the hard limit value for the number of disk files

3, Disk quota steps

1 Check if it is installed xfsprogs and quota software package

yum -y install quota
yum -y install xfsprogs

2 Mount the file system in a way that supports quota function

Add mount parameters “usequota,grpquota” Used to increase users , Group quota function support or

3 Edit quota settings for user and group accounts

[[email protected] /]# useradd jie
[[email protected] /]# echo "123123" | passwd --stdin jie
 Change user  jie  Password  .
passwd： All authentication tokens have been successfully updated .

4, Verify the disk quota function

chmod 777 /njzb_xm
su jie
cd /njzb_xm Verify disk capacity permissions
dd if=/dev/zero of=/njzb_xm/kgc.txt bs=10M count=12 Verify that the number of disk files exceeds the limit
touch {1..7}.txt
touch test{1..9}.txt
dd The command is a device conversion and continuous replication command
“if=” Specify the output device （ Or document ）
“of=” Specify the output device （ Or document ）
“bs=” Specifies the size of the read data block
“count=” Specify the number of read data blocks
/dev/zero" zero " Device file , You can provide empty characters indefinitely . It is often used to generate a file of a specific size

5, View disk quota

xfs_quota -x -c 'report - abih'
View disk quota
report Common options ：
-u： View for users
-g： View groups
-a： View quota usage reports for all available partitions
-b： Check disk capacity
-i： View the number of files

6、 ... and , Disk quota instance

 First installation xfsprogs and quota Two quota tools

 Mount the file system in the way of the previous quota function ,
 Add mount parameters “usrquota,grpquota”  Used to add support to users , Support for group quota function

[[email protected] /]# xfs_quota -x -c 'limit -u bsoft=40M bhard=80M isoft=8 ihard=10 jie' /saryn/

 Create user

 Set quotas for user and group accounts

 Verify the disk quota function 
 Give permissions and change users

 Go to this directory , Because the soft link for creating files is set to 8, The hard link is 10, So the first 11 Cannot create

 The next experiment , disk space , I need to use ddif Write something into it , First write 10M Write three times , No problem found

 Next , direct 90M More hard links than this disk

 Next, let's experiment with creating folders , It is found that the quota has been reached , could not be built

 View disk quota

test

useradd lisi
echo "123456" | passwd --stdin lisi
xfs_quota -x -c "limit -u bsoft=80M bhard=100M isoft=8 ihard=10 lisi" /home/ky21
xfs_quota -x -c "report -aibh"
chmod -R 777 /home/ky21/
su lisi
cd /home/ky21
dd if=/dev/zero of=/home/ky17/njzb.txt bs=10M count=12
touch ky21,.txt
rm -rf ./*
touch {1..10}.txt
touch 11.txt