When Surrey County Council decided to repurpose an existing IBM storage array, it was able to save 450 hours of staff time using a SAN-based solution from Brocade instead of LAN-based copy methods to transfer data between SANs.
The situation arose when the Council wanted to add capacity to its existing IBM SAN hardware but discovered it couldn't because its IBM FAStT 500 Storage Server was of such a vintage that expansion units could not be obtained which complied with EU environmental laws.
The local authority provides services to more than 1 million people and has some 10,000 IT users. Sheer growth of data meant that the Council had outgrown capacity on one of its IBM SANs which are 26 miles apart at data centres at Kingston and Guildford, a FAStT 700 and FAStT 500 respectively.
The Council could not add capacity to the FAStT500 in a way that was WEEE-compliant. WEEE is the European Union Waste Electrical and Electronic Equipment directive and in the case of IT equipment it specifies that the manufacturer is responsible for disposal of its component materials. FAStT500 expansion units that complied with WEEE were no longer available, meaning that if the Council used them, the system would have been unsupported by IBM, said Ross Walker, data centre and storage lead at the council.
"We couldn't procure expansion units that complied with the WEEE directive for their ultimate disposal," said Walker. "We could have got them from abroad or second hand, but they wouldn't have comprised a warranted system for that reason. So we were stuck with two SANs – one that could be upgraded and one that couldn't."
Surrey solved the issue by installing an IBM DS4700 at Guildford and moving the FAStT500 to Kingston as added capacity for the FAStT700 there. However, that solution required the storage team to move several terabytes of data -- some of it required 24x7 -- from the FAStT500 to the DS4700 before the old equipment was moved to its new location.
"We couldn't have the system down for any prolonged length of time," Walker said. "Our frontline staff, such as firefighters and social workers, need constant access and email, database and backups depend on the SAN. Also, any great time taken in copying data would mean catastrophic problems for some user data if it was saved but then not copied over because of the time lag."
Walker's team initially considered a PC LAN interface-based transfer such as FTP, Windows Copy, XCOPY or Robocopy. But, with all of these solutions came speed issues. "We needed to move 7 TB and if we were getting 20 Mbps on the LAN, that would have taken about two weeks," said Walker. Furthermore, if a block copy failed they wouldn't have been able to tell what had caused it and fixing it would have taken a long time.
At this time, the Council's IBM and Brocade partner, Tectrade, suggested the Brocade Data Migration Manager (DMM), a SAN-based Fibre Channel network device that moves data at SAN speed (4 Gbps at Surrey Council). With DMM, the data could be moved by SAN data migration in under a day.
The Brocade DMM device plugs into switches on both fabrics and creates a single zone. A storage administrator simply adds the LUN they want to migrate to and presses go, whereupon data is moved block by block. According to Brocade, it is a move process and not a copy process, which rewrites the location tables for the data.
Walker calculates the main tangible benefit as a savings of about 90% of the time that the data migration would have taken by using LAN-based copy methods. "It would have taken about 500 hours in staff costs using XCOPY or something similar," he said, "whereas we actually charged for 50 hours using the Brocade DMM."