Implementing software-based virtualized storage to manage more than 200 TB of mission-critical imaging data from two Manhattan-based hospitals was no small task for Continuum Health Partners Inc., a five-hospital system based in Secaucus, N.J.
The eight-month project involved not only the installation of DatCore Software Corp.'s SANsymphony, with the help of a DataCore engineer, but also new IBM storage subsystems and a new 2 Gbps Fibre Channel network infrastructure to enable synchronous mirroring among the SANs at the three sites.
The first step was getting the necessary buy-in from the radiology department's IT staff to use storage virtualization with its picture archiving and communication system (PACS), which stores digital images of MRIs, CT scans and ultrasounds. Continuum has separate teams for storage/backup, network/cabling and radiology IT administration, and the three needed to collaborate.
"That was a new process for us, asking our network service team to work with us to implement that," said Jesse Determann, senior manager of core enterprise infrastructure technology at Continuum Health Partners. "When we initially rolled out the solution, we were utilizing facilities that hadn't been used for storage before."
The team used single-mode fiber to connect the Verizon Communications Inc. equipment to its SAN switches when setting up the 2 Gbps Fibre Channel network for its two metro clusters. One cluster mirrors Roosevelt Hospital's midtown SAN to the Secaucus data center; the other links Beth Israel Medical Center's downtown SAN to Secaucus for multisite data protection and failover.
Moving on to the storage systems, the IT staff had to carve up the disk on the IBM controllers into logical volumes and serve it up to DataCore's Storage Domain Server (SDS), so the system could present the LUNs to the various application servers.
"If you're doing this in a mirrored environment, there's an order in which to do it," Determann said. "You do the IBM back-end piece. You do the DataCore virtualization piece first on the one side, and then once that side's completed, you start the IBM back-end piece on the second side of the mirror, and you add that disk to the Storage Domain Server on that side, virtualize it and then you set up the mirror.
"If you do those steps out of order, you can cause resource issues on that Storage Domain Server," he added. "You never want to be in a position where you're virtualizing storage on both sides of the Storage Domain Servers and you're also trying to bring a mirror up."
With mirrored systems, users can be shielded from any problems with the Storage Domain Servers or the back-end storage, Determann said. An administrator can take down the side experiencing the trouble, fix it and bring the mirrors back up without any interruption in service.
Prior to implementing DataCore SANSymphony-driven virtualized storage, Continuum had a number of smaller IBM SANs, with each one generally providing storage only to one application owner. With its DataCore deployment, the company purchased 10 larger IBM DS4800 and DS5300 storage systems and opted not to virtualize the older SANs, since it has no plans to expand them and eventually expects to migrate off of them.
Virtualizing the existing storage would have been a complex endeavor, necessitating the rezoning of the storage and the installation of new multipath drivers on the application servers to enable the Storage Domain Server to present storage to them, Determann said.
"Also keep in mind that when you serve up a volume from back-end storage to [SANSymphony], it virtualizes it. It zeroes it all out, so anything that you have on those volumes is gone," he said. "You can virtualize existing storage or storage that's not allocated, but anything that's already got data written to it, you'd have to migrate."
Benefits of virtualized storage . . . and the downside
To fully reap the benefits of virtualized storage, Continuum Health Partners migrated data in cases where applications in production were outside of the enterprise SAN storage. Benefits include the flexibility to grow the storage infrastructure and the systems that receive storage from it, continuous data protection due to the mirroring and management through a central interface.
On the downside, storage virtualization introduces an additional layer of management as well as troubleshooting, Determann noted. But the company would undertake the project again if it could turn back the clock, he said.
"The initial investment can be costly, but after you have the infrastructure and framework in place, the ability to manage storage needs and keep [the data] protected make it worth it," Determann wrote via email.
This was first published in June 2010