Redundant network storage

I'm looking for a way to achieve the following list of features. I think
I've taken a "wrong turn", so I'm backing up and reconsidering my opions.
Thoughts and recommendations would be very appreciated.

Loosely speaking, I'm looking for to provide storage service over a network
to a collection of machines over which I've little control. These machines
will be primarily Solaris and Linux, and "near POSIX" ACL support is
necessary. There should be no single point of failure. The various
machines receiving storage service are mutually untrusting. That is,
they're in separate security domains.

Up until now, the path I've been taking is a clustered NAS device. Each of
the NAS boxes has its own storage, and a separate interconnect keeps the
storage on each of these boxes in sync. The storage involved is *not*
using a real clustered file system, so only one of the devices can be
providing access to a given filesystem at any given moment. But the idea
is that the "virtual server" for a given filesystem floats between cluster
mebmers.

The product we've been investigating has been giving us some trouble,
however, and - once ACL support gets added to the mix - there appear few
alternatives that fit this exact model.

[FWIW, neither NetApp nor EMC support ACLs even in their NFSv4
implementations.]

As I said, I'm now backing up and reconsidering. One approach I'm
considering is a small cluster of NFS servers sharing a SAN with a
clustered file system. The CFS would permit each of the servers concurrent
access to the file systems, but failover/load balancing is still something
of an issue.

My storage needs aren't that great; one to four Tbytes would be fine for a
while. So a lot of SAN solutions are gross overkill for us.

Any thoughts or product recommendations? Frankly, at this point I feel like
I'm missing something obvious (there's a forest hiding somewhere behind
these damned trees {8^).

Thanks...

Andrew