Cache consistency problem for Virtualization high availability solutions

I took a look at Redhat Enterprise Linux HA and VMWare HA solution. It's easy to understand. Several physical servers can build a cluster. The system monitor the status of all VMs. If one VM is down, it can be restarted on other physical server. The applications on this VM can be restarted, too.

However, I have a question. In Guest OS, when most of applications write data to files successfully, actually the data are sent to OS cache (e.g., page cache in Linux) if direct IO isn't used. If Guest OS is crashed, some data may not be flushed to disks but Guest OS reports they have been successfully written. After the VM reboots on another server, it may find the data in disk is not consistent, and it may encounter data integrity problems. I don't find any information on introducing this problem for VM HA solutions. Don't we need to conside开发者_运维技巧r this issue?

I was asking a similar question here:
https://serverfault.com/questions/297980/sql-server-on-vmware-is-transaction-log-corruption-possible

Found this on VMWare, not sure how much it applies to your situation:

VMware hosted products on Linux hosts always use buffered IO … When using buffered IO, VMware hosted products do not bypass the host's buffer cache to produce crash consistent virtual machine IO. Consequently, if the IO is buffered within the host operating system, an application running inside a guest operating system on VMware hosted products might lose crash consistency.

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1008542