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Saturday, December 20th, 2014

Data storage management

EMC unveils real-time data replication over thousands of miles

EMC announced at its annual trade show today an upgrade to its data-caching appliance that allows storage arrays to replicate data between applications over distances greater than 2,000 miles.

The company also announced an integration of its Cloud Tiering Appliance and its midrange SAN/NAS VNX array, which allows older or unused data to be moved off the array to a lower-level tier of storage.

The EMC Cloud Tiering Appliance supports archiving to secondary storage with file retention capability, such as Data Domain, and will provide automated policy-driven migration, which allows users with big data challenges to automate data migration from multi-vendor environments to the VNX or to EMC Isilon clustered NAS storage.

Moving data was a big theme at this year's show, from placing it in virtualized storage and migrating it among tiers of storage to replicating it offsite for collaboration or disaster recovery.

At its user conference last year, EMC announced vPlex Metro , which allows synchronous replication of data over distances of up to 100 kilometers.

Today, the company announced VPLEX Geo, which allows data to be replicated between storage arrays over greater distances. Over the next 18 to 24 months it expects to announce VPLEX Global, which would allow data to be shared anywhere around the globe in real time, said Brian Gallagher, president of EMC's Symmetrix & Virtualization Product Group.

EMC partnered with several companies, including Cisco , Brocade, Silver Peak and Ciena, to use their WAN optimization technologies to achieve the data replication over distance.

In a question and answer session with press and analysts, Gallagher said the box only replicates data changes or updates and can only withstand a 50-millisecond delay between servers in geographically dispersed data centers.

"When an application comes through the [storage area network], the write is committed to disk as well as replicated to the remote site," he said.

The VPLEX appliance's "secret sauce" is its ability to tell applications such as Exchange, Sharepoint, or Oracle, that they're receiving the data in real time.

Cancer Treatment Centers of America (CTCA) just went live with EMC's VPLEX Metro technology. The hospital system is using VPLEX for high availability between redundant SANs -- an EMC VMAX Symmetrix and an NS960 array -- in the same data center rather than failing over to a secondary site - for now.

"We saw that if our VMAX was to fail, we needed some other type of redundancy," said Eric Sato, manager of server administration at CTCA. Sato said his company is considering using VPLEX Geo and Global eventually to replicate data to its brand new secondary data center in Madison, Wis.

CTCA hired consulting firm Ahead to help it with the VPLEX implementation. Eric Kaplan, president of technical consulting at Ahead, said CTCA is not atypical of many businesses that are looking for greater resiliency.

Limitations caused by the speed of light typically cause applications to time out when data is being replicated between machines over distance. This means that if a machine sending data does not receive confirmation from the recipient machine within a certain span of time, it considers the computer operation failed.

Typically, vendors have solved this problem by sending data asynchronously over distances, so that a response message is not required from the recipient machine. Asynchronous data replication, however, means that if a disaster occurs, causing a primary data center to go down, the data in transit to the secondary data center is lost. In order to share data in real-time, synchronous replication is required.