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Why does it happen?
The default behavior or on many Linux operating systems is to set a file system to read-only if critical information can't be written to disk. If this happens the file system is corrupt and fsck has to be run to fix it. The default behavior can be changed but it is not advisable. If it is changed to "continue" errors can accumulate and corrupt the file system. If it is changed to "panic" the system will halt and fsck will need to be run on the file system before it can be restarted.
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