WD has today released a report about possible data loss using WD Raid Manager and other similar software titles under OS X Mavericks

Direct quote from WD below

Dear WD Registered Customer,

As a valued WD customer we want to make you aware of new reports of Western Digital and other external HDD products experiencing data loss when updating to Apple’s OS X Mavericks (10.9). WD is urgently investigating these reports and the possible connection to the WD Drive Manager, WD Raid Manager and WD SmartWare software applications. Until the issue is understood and the cause identified, WD strongly urges our customers to uninstall these software applications before updating to OS X Mavericks (10.9), or delay upgrading. If you have already upgraded to Mavericks, WD recommends that you remove these applications and restart your computer.

The WD Drive Manager, WD Raid Manager, and WD SmartWare software applications are not new and have been available from WD for many years, however solely as a precaution WD has removed these applications from our website as we investigate this issue. .

Sincerely,
Western Digital

So with this in mind i have stopped the WD manager in OS X on my server ( System Preferences–>Users–>Login Items–> Remove the WD process in the list )

Now we need to wait for the updated version to come out from WD