Network Housing Group, which manages 17,000 properties in London and Hertfordshire, has overhauled its entire disaster recovery and data back-up systems using storage area network (SAN) technology from Atlanta Technology.
NHG had three storage areas to address. The first was the tape back-up system; the daily back-up and verification cycle was taking almost 24 hours, resulting in a very narrow window between one back-up cycle and the next. Furthermore, trouble-shooting and administrative tasks had to be done during the same limited time, leaving almost no room for errors. The second area was a lack of server-side disk space; while some older servers had available disk space, they were incompatible with the newer servers, making consolidation impossible. The final area was NHG’s disaster recovery plan, which had not been regularly tested and was potentially out of phase with recent changes in the operating environment.
Based on proposals from Atlanta Technology, NHG decided to address the three areas with a single solution. Atlanta’s solution was the deployment of one SAN at NHG’s head office and a second at a satellite office.
The head-office SAN array can support 10 terabytes of data, based on twelve 300Gb drives and the same number of 500Gb drives, while the satellite office SAN comprises twelve 500Gb drives, all based on Dot Hill R/Evolution hardware. Two Falconstor IPstor servers are coupled to the head-office SAN for storage virtualisation, while disaster recovery is supported via a third Falconstor server in the satellite office.
NHG now has two physical servers comprising 12 virtual servers that will eventually run Vmware. These run applications for areas such as invoice imaging, HR and intranet. NHG also has further physical servers running its housing management and financial systems – Northgate Housing and SUN Accounts respectively – and Microsoft Exchange. These have ‘snapshot agents’ installed to ensure consistency with the IPstor servers.
Mission-critical data is now replicated to the satellite office every hour, which has resulted in recovery time and recovery point objectives that can both be measured in minutes, enabling systems be brought back online very quickly in the event of a disaster. The hourly snapshots have removed the need for daily tape back-ups; these have been replaced with weekly tape back-ups taken directly from the SAN.
The storage capacity of the SANs is described by NHG as “future proof” over the lifespan of the hardware; they can be expanded to 56 terabytes, more than adequate to meet the foreseeable requirements of NHG.
