ATTOboy, says Nexenta as it lets you HA-ve a FibreBridge or two

NexentaStor MetroHA provides high-availability at city-wide distances for NexentaStor shared storage arrays, making it viable for high-availability needs.

NexentaStor's open source storage software involves controllers (heads) linking to the storage enclosures by ATTO FibreBridge 6500 rackmount controllers by 8Gbit/s Fibre Channel.

These ATTO boxes then talk SAS to the backend storage trays, adding four microseconds of latency. FibreBridges at different sites are linked so that if a Nexenta Stor controller fails at one site the other site can access its storage enclosures uing ATTO's FibreBridge infrastructure.

The NexentaStor head units can be up to 50km (30 miles) apart and they are effectively in a stretch cluster with the ability to load-balance between the clustered heads. Data is synchronously mirrored across the ATTO bridge between sites by MetroHA. In the event of a total site disaster, data services are restored at the secondary location within a matter of seconds, without any data loss.

There are some 25,000 FibreBridge 6500 installations world-wide so it's a dependable piece if kit.

Get a MetroHA solution brief here (pdf) and an Atto stretch cluster brief (pdf) here.

ATTO diagram of its stretch cluster componentry and linkage

What about costs? It ain't cheap. NexentaStor's list price per GB ranges for larger capacity (1PB) levels is $0.18/GB including support, with volume discounts. When purchasing NexentaStor with the separate MetroHA license, a Gold Level or higher support starting a $4,900, as well as on-site installation from a certified partner starting at $25,000, is required.

So that's $30k on top of your NexentaStor software costs and its hardware costs at the two sites. ATTO's FibreBridge 6500 has an MSRP of $6,495 so, with two of them, you're looking at $43,000, before sorting out the cross-city network links, to ensure metro-distance high-availability between two NexentaStor sites. ®