Linux based file systems become read-only

VMware has identified a problem where file systems may become read-only after encountering busy I/O retry or SAN or iSCSI path

failover errors.
 
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 host environment because ESX host

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.
 
These guest operating systems are affected:
•RHEL5 (RedHat)
•RHEL4 U6
•RHEL4 U4
•RHEL4 U3
•SLES10
•SLES9 SP3
•Ubuntu 7.04 

Note: This issue may affect other Linux distributions based on early 2.6 kernels as well, such as Ubuntu 7.04.
Solution
Note: This article does not supersede the Guest Operating System Installation Guide. A guest operating system upgrade may require an

ESX upgrade as well.
 
This Linux kernel bug has been fixed in different updates of different Linux distributions. Not all kernel versions include the

patch. Contact your Linux Distributor for more information.
•For RHEL5, upgrade to Update 1 (also referred to as RHEL5.1). For more information, see the RedHat Bug 228108.
•For RHEL4 U6, upgrade to kernel version 2.6.9-89.0.7. For more information, see the RedHat Bug 197158.
•For RHEL4 U3 and RHEL U4, upgrade to Update 5 (RHEL 4.5).
•For SLES10, upgrade to SP2. For more information, see the Novell Knowledge Base article 3605538.
•For SLES9 SP3, upgrade to SP4 or SP3 Maintenance Release build 2.6.5-7.286. For more information, see the Novell Knowledge Base

article 7005154.
•For Ubuntu 7.04, upgrade to 7.10.
Additional Information
As a workaround, remount the Linux file system using this command to return it to the proper state:
 
mount -o remount /
 
Note: It is ideal to identify the problem and resolve the issue rather than performing this workaround when this situation arises.
 
For translated versions of this article, see

See link:

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=51306