Announced to be available in July 2014, Fujitsu adds support for transparent failover to their Eternus DX S3 family. Starting with the DX200 series a synchronous mirror with any other Eternus DX200 S3 model (or higher) is available with added support for transparent failover. This brings enterprise level storage availablitity to the entry level. Especially as you have controller redundancy on the storage system level as well. This seems to be a big advantage to systems like DataCore or NetApp.
The new feature requires tow DX200 S3 systems (or higher), REC licenses on both systems (Remote Equivalent Copy, a well known feature in the Eternus disk storage systems), FC connectivity and a whitness server (called TFO server, which can be a physical or virtual server). With this setup a datacenter outage can be tolerated in a transparent way.
With it's initial release you have to use FC as SAN protocol, perhaps newer versions will also include support for iSCSI, FCoE and even SAS. Also if you use the Eternus as unified storage (this is you use the NAS feature) this is not supportet for transparent failover. Only blockstorage will be supported with the current version.
In combination with (extra licensed) features like AutoTiering and Thinprovisioning you can built up a highly redundant, highly scalable and highly performant SAN on entry-level hardware.
Probably with all these features licensed the price will be more in the mid-range market than in the entry level and also some typical problems are currently unknown how they are addressed like split-brain or what if the TFO server is unavailable during failover.
But as far as I can see, the already very good Eternus storage systems will get even better and I'm really curious how well they perform once this feature is general available. Especially in comparision to DataCore's SANsymphony-V, NetApps Metro/stretched cluster or EMCs VPLEX.