The biggest knock against the X4500 I’ve heard is that it is too expensive. From a storage perspective it is actually absurdly cheap compared to the 5-10x charged by the name-brand storage vendors – and for lower data integrity than the X4500/ZFS system offers.
Considered as a server it is a different story. After all, the most popular servers are in the $1k-$5k range, so why not just glue the disks on with some cheap PCI-X adapters and be done with it?
Several reasons, as this brief post at c0t0d0s0.org notes. He points out some of the trade-offs that low-cost servers make in order to meet their price points, like bottlenecked architectures that offer connectivity at the expense of performance.
Sun’s server group should get some benchmarks out pronto of the X4500’s iSCSI and NFS performance, along with some TPC numbers. That is risky, since the storage group might hijack it out from under the server group. Yet the storage folks have their hands full with staff turnover – always a problem, but much worse right now – and the struggling STK integration effort. People need to see what this machine is capable off, sooner rather than later.