Virtual storage via HDS USP VM disk array helps Canadian city upgrade to VMware ESX Server 3.5
The City of Coquitlam, B.C., backed into virtual storage
18 months ago as part of an upgrade from VMware Inc.'s ESX Server 3.0 to Version 3.5. When the Vancouver suburb's IT shop discovered its aging Hitachi Data Systems (HDS) Corp. Thunder 9570 disk arrays
weren't certified to work with VMware's new server virtualization software, it went looking for a new storage back end. After considering NetApp Inc.'s V-Series and IBM's SAN Volume Controller (SVC), Coquitlam settled on HDS' Universal Storage Platform VM (USP VM
) -- the lower-end counterpart of the vendor's USP V storage system -- in part because of the potential benefits of controller-based storage virtualization
The city figured that virtual storage would not only help to extend the life of its Thunder 9570s, but also potentially front its Nexsan Corp. ATABeast backup/archive appliance to enable the IT staff to view all of its storage systems as a single pool.
Under the USP VM approach, Coquitlam didn't need to re-create the same-size LUN from one of its 9570s and transfer over the data. Rather, the LUNs on the Thunder 9570 were ingested into the USP VM, according to Andrew Tolentino, a senior storage architect at Compugen Inc., a Canadian systems integrator that worked with Coquitlam and also done installations of other vendors' storage virtualization systems.
"It's as if the LUN itself was coming off the 9570 and being presented back to the host itself," through the USP VM, he said. "The USP VM would now own the LUN, and from that point on, you present the LUN that the USP VM owns back to the host."
Purchasing a third-party vendor's disk array, by contrast, would have involved data transfer and downtime, Tolentino said. Another potentially thorny issue, changing multipathing software, didn't come into play because Coquitlam stuck with the same vendors.
"If you present the Hitachi USP VM with a LUN from a different system, it simply attaches to it and virtualizes it, whereas with the NetApp and IBM solutions, you had to reformat that LUN into the NetApp and/or IBM formats," said Darren Browett, technical services manager for the City of Coquitlam. "The Hitachi box is a five-nines box, but in the event there was a catastrophe, we could take those original LUNs and attach them back to a server again and carry on and not have to do anything."
The city has two Thunder 9570s, one at the primary site and one at the disaster recovery
site, and some of the LUNs on each 9570 are virtualized. If the USP VM fails, Coquitlam can revert back to its old storage, and the Thunder 9570 LUNs would still be accessible.
Browett also liked the idea of being able to move data from one disk array to another for maintenance without having to take down the system and potentially incur overtime costs.
Implementing virtual storage and virtualizing LUNs
Implementing virtual storage in tandem with a new VMware server farm, a new QLogic Corp. SANbox 9200 core switch and the new HDS USP VM SAN gave the project the feel of a greenfield deployment, even though Coquitlam already had a SAN. The city spent two to three weeks integrating its original SAN with the new SAN fabric with the help of Compugen.
The only glitch was a one-day outage related to a power struggle between the new QLogic switch and the old Brocade Communications Systems Inc. switches. Coquitlam wanted its new QLogic switch to be the master, but an old Brocade switch claimed control, triggering a day of troubleshooting with Compugen.
"Once we figured out the command, it came up," Browett said. "We could have been done in a half-hour if we knew that command."
Virtualizing LUNs from the city's different storage systems was a simple process, according to Browett. "You make sure the LUN is inactive, present it and say, 'I want to virtualize that LUN.' That's it. Then you bring the server back up that uses that LUN," he said.
The IT staff does have to take the LUN offline for approximately 15 minutes to virtualize it, but that's the main challenge, according to Compugen's Tolentino.
"Most IT shops run 24/7, and you still have to take it down. But instead of having a bigger outage, there's a smaller window [with the HDS system] because you just have to virtualize the LUN. You don't have to move data," Tolentino said.
The City of Coquitlam now has approximately 20 TB of virtual storage through its USP VM and hasn't noticed an impact on performance or done any special monitoring or management. The city plans to migrate the remainder of the LUNs from its Thunder 9570s to the USP VM during the next year.
"That's for me where the storage virtualization's going to come into play," Coquitlam's Browett said. "As I need to move my data around as storage arrays become end of life or end of support, I can slowly migrate that data off of the old SAN into a new SAN or a new storage array without creating any downtime or other issues for my users."
This was first published in June 2010