The real question is: Can the LUN actually be used (read/write) by two or more servers and a common application like Oracle at the same time and maintain data integrity?
The answer to that question is a qualified "yes," if you are using some form of volume and/or file synchronization software such as a clustered volume manger, a clustered file system (CFXS), a network file system using NFS or CIFS or a clustered application like Oracle Real Application Clusters (RAC).
Without using some form of software on the servers or a NAS device, there is no way of coordinating access to changed data blocks and maintaining data integrity. So, if all you want to do is to have shared access to a group of files or tables, your options are to either use NFS or some type of clustered application or clustered file system.
This was first published in September 2005