The CentOS system has an IO error.

The CentOS system has an IO error.
After deleting the soft link, the new problem arises: I am going to create a new folder ntfs in the/mnt directory to mount the mobile hard disk. As a result, when I enter mkdir/mnt/ntfs, this prompt is displayed directly to me:
Mkdir: the directory "/mnt/ntfs" cannot be created: Read-Only File System
Grandpa, I just created a new/mnt/fat folder yesterday. Today I am told that it is a read-only file system ?! If you don't believe it, add the 777 permission: chmod-R 777/mnt. The result is still displayed:
Chmod: Change "/mnt/" permission: Read-Only File System
Chmod: Change "/mnt/fat" permission: Read-Only File System
Under what circumstances, cannot I change the permissions of the root user? Check other partitions, such as cd and mkdir 123. Continue with the prompt:
Mkdir: the directory "123" cannot be created: Read-Only File System
The root folder is also read-only !!!!! It should be because of a system problem. Check the log file vim/var/log/messages and report an error, IO error ......
I remembered that I pulled out the old SATA hard drive umount on the server yesterday and caused an I/O error. Then the system automatically sets read-only protection !!!
Get used to killing people! Usually, mobile hard disks are directly pulled after umount ...... Hurry up and fix it. First move the hard disk, cp-R-v important information, and then use the fsck command to save the poor hard disk! Fsck usage: fsck-t ext3-r/mnt
Filesys: device Name (eg./dev/sda1), mount point (eg./or/usr)
-T: specifies the type of the file system. This parameter is not required if a definition is already defined in/etc/fstab or is supported by the kernel.
-S: Execute The fsck command one by one in sequence to check
-A: Check the partition of all columns in/etc/fstab.
-C: displays the complete check progress.
-D: print the debug result of e2fsck.
-P: When both-A conditions exist, multiple fsck checks are executed together.
-R: if both-A conditions are available, this parameter is omitted/not checked.
-V: Detailed Display Mode
-A: If the check is incorrect, it will be automatically repaired.
-R: if the check is incorrect, the user will answer whether the problem is fixed.