File system errors.
File system errors can be caused by power outages and disconnects that prevent the file system from completely writing the data to the RAID array. It can also be caused by problems with hardware, system crashes, and drivers. This will result in the file system being left in an inconsistent state in which you can see a variety of issues: loss of all shares, slow data transfer and, if not repaired, it could result in a loss of data.
Running File System repair will resolve the above issues. Linux does perform a file system check upon system startup, however, it is rather perfunctory.
In order to perform the File System repair, you must run a memory test first to determine if your system is memory-error-free. If the memory test comes up clean, you can then run the File System repair. If you run the FS repair without knowing whether you have memory errors, the repair can damage your data.
To run the memory test, restart your server and hit 'Esc' right after the system performs POST, you'll then get the option to run the test. It's best to let the memory test run until it's completed.
To run the FS repair, go to the Console Extended Tools: