Gentoo: SCSI disk on VMware guest goes into read-only

[ATC]

In a heavily loaded VMware environment, we have a Gentoo Linux server which goes into read-only mode after a few days. Attempts to remount the disk fails with the message normally seen when mounting CD-ROMs etc: /dev/hda3 is not writeable, mounting as read-only.

The only solution seems to be rebooting the server on a regular basis.  

[ATC]

This error is normally caused by a kernel bug (reportedly in the 2.6.20 thru 2.6.22 kernels), triggered by heavy IO load in a VMware environment.

There are three possible workarounds, these may be combined:
1) Include the mount option 'barrier=0' in /etc/fstab
2) Change error-handling behaviour with 'tune2fs -e continue /dev/sda'
3) Increase fault-tolerance for the device with 'echo "60"> /sys/block/sda/device/timeout' during startup

Note that the real solution is ofcourse to upgrade the kernel. You may also want to look into the IO performance issue that is triggering the problem in the first place.