According to VMware KB Article 51306

VMware has identified a problem with RHEL5, RHEL4 U4, RHEL4 U3, SLES10, and SLES9 SP3 guest operating systems. Their file systems may become read-only in the event of busy I/O retry or path failover of the ESX Server’s SAN or iSCSI storage.

This issue may affect other Linux distributions based on early 2.6 kernels as well, such as Ubuntu 7.04

The same behavior is expected even on a native Linux environment, where the time required for the file system to become read-only depends on the number of paths available to a particular target, the multi-path software installed on the operating system, and whether the failing I/O was to an EXT3 Journal. However, the problem is aggravated in an ESX Server environment because ESX Server manages multiple paths to the storage target and provides a single path to the guest operating system, which effectively reduces the number of retries done by the guest operating system.

And the solution is:

This is not an ESX Server bug. This Linux kernel bug has been fixed as of version 2.6.22.

Note: This article does not supersede the Guest Operating System Installation Guide, a guest operating system upgrade may require an ESX Server upgrade as well.

For RHEL5, the resolution is to upgrade to Update 1, also refereed to as RHEL5.1

For RHEL4 U3 and RHEL U4, the resolution is to upgrade to Update 5, also refereed to as RHEL 4.5.

For SLES10, the resolution is to upgrade to SP2. For more information, see Novell KB TID 3605538.

For SLES9 SP3, the resolution is to upgrade to SP4, or SP3 Maintenance Release build 2.6.5-7.286.
For more information, see TID 3584352 – Filesystem goes read-only in VMware

For Ubuntu 7.04, the resolution is to upgrade to 7.10

Beside that,  I would also suggest you check Novell Support @

• Ext3 filesystem goes read-only without the underlying storage reporting errors
• Filesystem goes read-only in VMware

Hope you won’t need to go through unnecessary step. Enjoy!