| Q: We have two load-balanced Web servers that read and write to the same LUN. How can we have concurrent write access to our EMC SAN without corruption?
A: Achieving safe, secure data storage access for shared read/write IO operation while maintaining data consistency usually requires data sharing software, which includes shared SAN file systems from Quantum and SGI, as well as distributed or networked file systems that support NFS and Windows CIFS-based access. NAS products would enable your servers to access data for concurrent shared read/write access with data consistency.
From an EMC-specific perspective, you'd probably need a Celerra NAS appliance or gateway product, or a server with either direct-attached SAS, iSCSI or Fibre Channel NAS running Microsoft WSS configured as an NFS and CIFS file server.
--Greg Schulz, founder and senior analyst, StorageIO Group