Case Study: Unified storage sorts out a Surrey hospital file problem
Three separate PACS silos avoided in SAN/NAS design
File storage silo proliferation at The Royal Surrey County Hospital was avoided through use of ONStor's clustered NAS product. RSCH is a medium-sized 520-bed district general hospital, located in the heart of Surrey, serving a population of 260,000 for general services and 1,200,000 for specialist cancer care.
It was implementing a storage area network (SAN) to speed up data access and gain the benefits of a consolidated data storage entity. However, this regional healthcare provider was also xpanding its diagnostic capabilities with radiology and cardiology PACS (Picture Archiving and Communication Systems) from two different suppliers: GE and Heartlab. Given the nature of the data being stored such as X-rays, reports and patient records, the new PACS would require a lot of storage capacity – starting at over 20 terabytes.
The accepted industry practice was to house data in separate silos, one for each PACS. That would have meant two new storage environments in addition to the McKesson Health Information System already in place. Managing three separate pools of data storage and archive within a single facility seemed highly inefficient, so the hospital's IT managers sought a better approach.
Conventional network-attached Storage (NAS) appliances had three significant shortcomings in the view of the IT department. Firstly, high acquisition cost was a major consideration. The hospital's initial implementation required over 20TB of storage. The NAS appliance and the NAS heads alone would have cost nearly half a million dollars, not including storage.
The second shortcoming was limited scalability. When the PACS outgrew the capacity limitations of the initial NAS appliance, they would be forced to add more, thus putting them back in the exact scenario they were trying to avoid in the first place, using multiple islands of storage.
Thirdly, limited open storage support was highlighted as a shortcoming, although the NAS appliance vendor offered a "gateway" version, the IT managers realised this product had the same scalability and cost issues as the vendor's conventional NAS offerings.
Furthermore, their open storage support came at a high price: 30 percent of the available capacity would be lost to the vendor's file system overhead.
File access on the existing clustered Windows servers and others was becoming slow and suffered from outages.
A clustered and scalable NAS gateway
After surveying the options, NAS appeared to be the clear choice for PACS data consolidation. Since NAS employs open-standard communication protocols (CIFS and NFS), it is compatible with their PACS and HIS environments.
Furthermore, these protocols would make it simple and secure for remote users (such as physicians and clinics) to directly access data over IP.
But RSCH wanted NAS benefits without NAS limitations. Systems house Eurotech Computer Services provided them by, in simple terms, layering a NAS head or gateway onto the SAN it was already designing for RSCH.
The SAN came from Sun/StorageTek arrays with Brocade providing the SAN fabric infrastructure. ONStor provided the NAS gateway and the three suppliers' kit was installed by Eurotech.
ONStor NAS Gateways met the primary objective of delivering a highly available, highly scalable solution. Four elements made the ONStor solution a good fit for the RSCH environment: scalability; availability; open storage; and cost.
With regard to the conventional NAS limitations described above, the ONStor/Brocade/Sun/StorageTek product set was able to provide an answer to all three. As the front end ONStor would like to think it was the gateway to these benefits.
- One objective of the hospital's IT managers was to leverage their existing storage hardware and software. ONStor gave them that flexibility. It is open-ended in that any supplier's SAN kit can be bolted on to it.
- With the initial implementation at 20TB; scalability was critical to this hospital. The ONStor environment scales to 40 petabytes within a single storage pool, permanently freeing them from the management issues inherent in multiple storage silos.
- ONStor offered an acquisition cost 65 percent lower than the competing NAS appliance vendors.
As data availability directly impacts the quality of patient care, ONStor's n-way clustering architecture provides multiple levels of redundancy to ensure that data is always available.
The SAN behind the gateways
This ONStor product implementation is nearing its first year of operation. Over 2,000 users have been transferred from a mixture of Windows and other file systems to the ONStor system. There were several data migratio issues to be overcome in moving data from aging Windows clusters systems and other legacy kit.
The gateway is an ONStor Bobcat 2240 in a HA (High Availability) configuration for load balancing and automatic failover, with SUN/StorageTek enterprise-class tiered storage using both Fibre Channel and serial ATA (SATA) disk drives. This is a FlexLine FLX 210, supplied with 2.7TB of Fibre Channel (FC) disk and 3.5TB of SATA. Only 9 trays of the 14-tray FLX210 were populated at installation time. Since then the Fibre Channel disk capacity has been increased to 4.2TB.
RSCH had felt increasing pressure over backup windows becoming longer and longer. That issue was resolved as well. It has implemented a new backup strategy utiliising Symantec/Veritas NetBackup with a 'disk to disk to tape', design, using the Sun/StorageTek tiered (FC-->SATA) storage. RSCH bought a Sun StorageTek 60-slot L80 library with LTO2 drives and tape cartridges.
A Brocade SAN fabric enables high speed access for the addition of various databases, with high I/O block level handling requirements.
Eurotech provide onsite IT services with dedicated engineers assigned to the site for instant familiarity for supported systems, leading to faster problem solving.
RSCH now has a unified SAN+NAS storage infrastructure. Block-level accesses to SAN data come in from servers via the Brocade switches to the FLX array. File-level requests come in from application servers to the Bobcat which then sends them on as block-level requests over Fibre Channel to a Brocade switch and on to the FLXD array again.
For The Royal Surrey Hospital Trust there were three immediate business benefits, notably:
- Scalable NAS gateway consolidated data, thereby saving cost
- N-way clustering ensured continuous availability
- Open storage enhanced purchasing flexibility.
Simon Mortimore, RSCH Trust's information manager, said: "The ONStor NAS solution provides impressive data throughput and availability together with a much reduced management overhead, while the SUN/StorageTek SAN has future-proofed the data storage needs of the Trust for the next few years with plenty of scope for expansion, and anxiety about our back-up window is a thing of the past. Once we had overcome the challenges of data migration, the benefits of this solution became immediately apparent."
As of 2007, the Royal Surrey County Hospital, including St. Luke’s Cancer Centre, is under threat of closure. A review being conducted by McKinsey & Co for the South East Coast Strategic Health Authority is considering options including the total or partial closure of the hospital.