What happens when disk space is full???

First case: there is not enough disk space left for a block (df-h)

Second, there is not enough disk space left for inode (df-i)

Show no space left on device
block space is full, storage is too large
inode is full and produces lots of small files

1. Index Node Information - inode and blockde

The difference between inode and blockde:

1. What do inode and blockde do?

inode:(index node)Index node information used to store data---Some properties of a file or directory (the permissions for a file belong to a group of users)
block:              block           For storing data---True data information for the file

2. How did inode and blockde appear?

Only after the disk is well formatted will there be a file system inode and block(Pouch)
Creating a file takes up at least one inode And a block

3. How inode and blockde query for information

inode Information viewing method:
[root@VM-0-3-centos ~]# df -i
Filesystem      Inodes IUsed   IFree IUse% Mounted on
devtmpfs        232347   329  232018    1% /dev
tmpfs           235251     7  235244    1% /dev/shm
tmpfs           235251   422  234829    1% /run
tmpfs           235251    16  235235    1% /sys/fs/cgroup
/dev/vda1      3276800 81268 3195532    3% /
tmpfs           235251     1  235250    1% /run/user/0

block Information viewing method:
[root@VM-0-3-centos ~]# df -h
Filesystem      Size  Used Avail Use% Mounted on
devtmpfs        908M     0  908M   0% /dev
tmpfs           919M   24K  919M   1% /dev/shm
tmpfs           919M  476K  919M   1% /run
tmpfs           919M     0  919M   0% /sys/fs/cgroup
/dev/vda1        50G  3.5G   44G   8% /
tmpfs           184M     0  184M   0% /run/user/0

4. Why do df-h and df-i both show disk usage, but are they so different?

df -h   Is to delete files that are relatively large and useless   --- Large files occupy a large amount of disk capacity.
df -i   Remove too many small files   --- Too many files consume a lot of inode Number.
PS:If df To see any disk space that is full, you need to delete files from the file and clean up the space

2. Insufficient disk space block remaining (df-h)

Looking at the disk capacity through the df-h command, we found that / dev/vda1 has a larger capacity

[root@VM-0-3-centos /]# df -h
Filesystem      Size  Used Avail Use% Mounted on
devtmpfs        908M     0  908M   0% /dev
tmpfs           919M   24K  919M   1% /dev/shm
tmpfs           919M  468K  919M   1% /run
tmpfs           919M     0  919M   0% /sys/fs/cgroup
/dev/vda1        50G  3.5G   44G   8% /
tmpfs           184M     0  184M   0% /run/user/0

Enter the /(root) directory and use du-sh * to see the capacity size of all directories under the /(root) directory

[root@VM-0-3-centos ~]# cd /
[root@VM-0-3-centos /]# du -sh *
0       bin
123M    boot
4.0K    data
0       dev
37M     etc
4.0K    home
0       lib
0       lib64
16K     lost+found
4.0K    media
4.0K    mnt
127M    opt
0       proc
72K     root
476K    run
0       sbin
4.0K    srv
0       sys
19M     tmp
2.7G    usr
408M    var

Found usr directory occupies large capacity, enter usr directory to continue du-sh *investigation

[root@VM-0-3-centos /]# cd /usr
[root@VM-0-3-centos usr]# du -sh *
277M    bin
4.0K    etc
8.0K    ftp
4.0K    games
33M     include
774M    lib
345M    lib64
98M     libexec
504M    local
79M     mpi
55M     sbin
394M    share
184M    src
0       tmp

Continue to view capacity in the larger-footprint directory src

[root@VM-0-3-centos usr]# cd src
[root@VM-0-3-centos src]# du -sh *
8.8M    debug
77M     kernels
8.0K    mlnx-ofa_kernel
4.0K    mulu
62M     ofa_kernel
37M     ofa_kernel-5.1
4.0K    wenjian

PS: This operation simulates a situation where directories or files already need to be cleaned up
Now that you can find out which files are taking up a lot of memory, we'll use the mulu (directory) and wenjian (file) created by my own simulation as the test objects.
1. Clean up the files in the /usr/src/mulu directory.

[root@VM-0-3-centos src]# rm -r /usr/src/mulu/*
rm: remove directory '/usr/src/mulu/fu'? y

2. Clean up the Wenjian files in the SRC directory of /usr/src/wenjian
Empty the contents of the file with the redirected command (and there are other ways to empty the contents of the file without demonstrating them all)

[root@VM-0-3-centos src]# echo " " >> /usr/src/wenjian

3. Insufficient disk space inode surplus (df-ih)

Plus h because it directly outputs units of capacity that people can see directly

Looking at the inode under df-ih, it is found that the usage of the inode value under the root directory is 100%

[root@VM-0-3-centos ~]# df -ih
Filesystem     Inodes IUsed IFree IUse% Mounted on
devtmpfs         227K   329  227K    1% /dev
tmpfs            230K     7  230K    1% /dev/shm
tmpfs            230K   420  230K    1% /run
tmpfs            230K    16  230K    1% /sys/fs/cgroup
/dev/vda1        3.2M   3.2M  0      100% /
tmpfs            230K     1  230K    1% /run/user/0

Solution: Check through the following script to see which directory has the most files under it

[root@VM-0-3-centos ~]# find / -xdev -printf '%h\n' | sort | uniq -c | sort -k 1 -n

Ultimately, the maximum number of files was found in the / usr/local/tomcat directory. Then it became clear that there were millions of files under the / usr/local/tomcat/logs directory, which should be logs accumulated over time by long-running applications, deleting all files in that directory, and using the xargs command to delete a larger number of files

[root@VM-0-3-centos ~]# ls | xargs -n 10 rm -rf