Why my centos ext3 filesystem go read-only?

Question

My centos ext3 filesystem go read-only random(only the /var partition). When i reboot it, i will changed back to rw. os: centos 5.4 partition: /var, size:80G the /var is for web logs and mysql data file.

Answer 1

(Voted to move to serverfault.com)

Likely you have a hardware problem with your disk, or corruption from some other reason. When a file system errors is detected, the filesystem is usually remounted read only.

Answer 2

Possibilities are:

1. Ext3 filesystem errors
2. Disk IO bottleneck OR HDD issues.

First thing you must check whether the HDD IO and it's functionality, performance. In order check the IO please take a look into this question.

iostat -x -d 

(will do the trick)

If you have filesystem error, boot your server into single user mode then run,

fsck -a -f

this will resolve your filesystem issue.