[CentOS] redundant networked secure file system recommendation

Hi all,

We are currently running a NFS-based server centric setup. I would like to set up something where I can easily have more than one redundant server, security/authentication (this part seems a little flaky with NFS, at least did several years ago), with the capability to easily add/remove servers as necessary, take redundant servers down for maintenance, etc. Total volume we expect to run on the server side will be somewhere between 10-30 TB. The servers will most likely be CentOS machines, the clients mostly Linux machines with some Macs and possibly Windows (the latter part not that important).

Any insight, thoughts and recommendations will be much appreciated.

Thanks.

Boris.