Identifying Disk Corruption and Filesystem Errors – cPanel

Symptoms

Notice: Due to the nature of disk & filesystem corruption, there is a risk for potential data-loss, as such, cPanel support staff can't guide you nor perform any disk or file system recovery on your behalf. If you are not comfortable repairing these issues, we recommend reaching out to your hosting provider or system administrator for assistance.

You may find none, one, or more of the following symptoms if your filesystem or disks are failing:

Files go missing
Some files are found empty
Files contain data from other files on a different location on the server
Databases may be corrupted
Binary files may become corrupted
Filesystem errors in dmesg and /var/log/messages
Elevated IOWait when checking the sar utility
Poor disk performance
Others not listed here

Description

Please keep in mind that cPanel support is not able to assist with disk failures or issues related to filesystems on your server. This information is provided as a courtesy.

Disk Failure and Filesystem errors represent a critical problem that requires immediate action in order to mitigate the potential for data loss. If you believe it could be possible that your filesystem or disk is failing, you should contact a systems administrator with the skills, training, and expertise required to handle the situation for you. Sometimes, you may need to involve your hosting provider or datacenter if the hardware is failing on your server. Please see the "Additional Resources" section below if you need help finding a systems administrator.

Procedure

The easiest way to identify potential disk or filesystem problems is to check dmesg, and /var/log/messages.

You can do this by running the following commands:

grep "\-fs" /var/log/messages

dmesg | grep "\-fs"

journalctl -b | grep "\-fs"

Although the above commands will often uncover most filesystem-related issues, it is very important that you manually review the full contents of those logs to verify that no filesystem errors are contained within the logs.

Once you review the logs, most of the time the logs will reference a specific disk. You can see which disk is being referenced and where the disk is mounted with the following command: