Boris,

On Wednesday 25 April 2012 17:58:39 Boris Epstein wrote:
> I am running VirtualBox 4.1 on CentOS 6 and I got this warning that putting
> your VM's into an XFS filesystem is risky. I have also heard some rumors on
> the net to this effect. Does anyone know in more detail what's behind those
> rumors?

Linux kernels < 2.6.36 have a bug with direct I/O (bypassing the kernel
cache). As CentOS 6 ships 2.6.32 it might have this bug or the RedHat
guys backported the fix from later kernels. Actually 2.6.32 from CentOS/
RHEL isn't really 2.6.32 vanilla but some special kernel. I really don't
know if these kernels have the bug fixed or not.

VirtualBox will just check the kernel version number and use the old-style
cached disk access on CentOS6 if the file system is ext4 or xfs. There
is no further action required, VirtualBox will switch to 'host caching'
mode and the user does not need to care. And in this mode there shouldn't
be any problem. And the warning is logged into the VBox.log file.

Kind regards,

Frank
-- 
Dr.-Ing. Frank Mehnert
Senior Manager Software Development Desktop Virtualization, VirtualBox
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