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Block virtualization case study #2: HDS USP V Storage virtualization and thin provisioning help a Midwest financial firm manage server growth, avoid resource constraints, and delay the purchase of a large array. By Dave Vellante February 20, 2008—CS3 is a financial industry leader migrating to an IT model that relies on a "flat" or horizontal server approach, meaning it uses many smaller servers rather than smaller numbers of large servers. This proves challenging for the storage group because CS3 is often rolling in dozens of new servers each week. The company's storage group struggled to continuously provide adequate resources for application users and turned to storage virtualization and thin provisioning to help solve the problem. Pain points
As such, the firm's practice was to over-provision storage to allow for headroom. According to the executive in charge of storage operations: "It was common for us to provision 400GB to a server when its applications really only needed 50GB." Solution strategy CS3 is about nine months into the project. In the first two months, the company received management approval to start evaluating the capabilities of the USP V and has since rolled out the solution for its test and development environment. The Sun/Hitachi array supports virtualization and thin provisioning for both internal arrays and externally attached arrays from a variety of vendors. CS3 is currently using only the internal virtualization and thin-provisioning ("Dynamic Provisioning") capabilities of the USP V and has begun to evaluate both of these features for externally attached storage. (See table below.) Adoption issues CS3 needed to learn some new concepts related to virtualization and thin provisioning. The storage team used the GUI that came with the Sun/Hitachi array to manage the virtualization and set up resources such as port allocations. Another adoption issue was related to procurement practices and thin provisioning. Because thin provisioning essentially "fakes" the application into believing it has more storage than is physically available (avoiding over-allocation), when thresholds were met and CS3 had to acquire additional storage, previous procurement practices were exposed as too lengthy. It quickly became clear the procurement process was problematic and needed to be improved or applications would be at risk of crashing. CS3 put in place a new streamlined procurement process to accelerate the approval of storage purchase orders. Benefits The approach allowed CS3's test and development organization to use less expensive servers, which served its horizontal server strategy. The key benefit of the virtualized storage infrastructure was the ability to easily and quickly provide storage and connectivity to a rapidly growing server farm. Despite the substantial initial migration and setup costs, a significant benefit for CS3 was that thin provisioning allowed the organization to put off purchasing an entire array, estimated at more than 40TB, which translated into a net savings of several hundred thousand dollars. Implementation CS3 chose to only use virtualization on 40% of the Sun/Hitachi internal storage array. The company applied thin provisioning to the virtualized portion of the array by spreading data in very small chunks across a wide span of devices, creating one large pool of storage. CS3 was immediately able to reclaim wasted space—as much as 300GB per server across dozens of servers. In total, over a nine-month period CS3 estimates it recaptured approximately 40TB of over-allocated storage, allowing it to defer a previously planned array acquisition. Organizational issues Once CS3 was comfortable with the behavior of the system it turned its attention to the new business process related to procurement. Thin provisioning exposed a shortcoming in the procurement process whereby when storage pools run low, then physical storage needs to be added immediately and delays in a purchase order process can be critical. CS3 implemented an approach that reduced the number of signoffs required and allowed for multiple signatories in the event key people were out of the office. While seemingly trivial, this change was crucial. Best practice To offset these costs there must be enough change of server and storage resources to justify the expenditure. To the degree that this is the case, saving several hundred thousand dollars (as was the case with CS3) within a year is feasible. This move could also save organizations tens of thousands of dollars for each array migrated. For companies that have arrays rotating on three-year leases, for example, this can bring significant savings once the initial migration is completed. The other advice CS3 offers is to limit the complexity of storage resource management (SRM) tools. CS3 does not believe in an umbrella-based SRM approach and recommends mastering the native tools that come with storage systems. While this puts extra load on the storage administrators, CS3 believes mastering native tools is ultimately more effective than trying to achieve a one-tool-does-all strategy. Conclusions A practical focus on reclaiming wasted storage space enabled CS3 to demonstrate quantifiable return on investment to upper management. Moreover, once the initial migration to the virtualized arrays was completed, CS3 benefited from more rapid addition of new capacity and migration of existing arrays and servers, non-disruptively. Nonetheless, CS3 had to overcome some initial migration disruption and other costs associated with moving to a virtualized, thinly provisioned environment. Despite some initial concerns about the performance and reliability of the approach, CS3 reports very positive results. Going forward, CS3 has the opportunity to extend virtualization and thin provisioning to external capacity attached to the USP V. This is forthcoming and will further support the integration of an increasingly diversified installed base of arrays. Moreover, as CS3 begins to implement server virtualization, the pace of server change will escalate and the company will be well-positioned to respond. It is unclear at this time if CS3 will drive this strategy to the production environment. Concerns about the performance and novelty of thin-provisioned volumes loom large, and the company is biding its time to gain more experience with storage virtualization and thin provisioning. Dave Vellante is a co-founder of The Wikibon Project, an open community of practitioners, consultants, and researchers dedicated to improving technology adoption. He can be contacted at david.vellante@wikibon.org.
CS3 is a financial services company with more than one petabyte of open systems storage installed across several hundred Unix, Windows, and Novell servers. The company also runs mainframes and attached storage isolated from the open systems infrastructure. The firm has multiple data centers, including two synchronously connected centers and a third disaster site that runs asynchronously. Including mainframe attachments, the company has nine EMC DMX arrays and seven Sun/Hitachi arrays, such as USP V and TagmaStore systems. Nine months into a multi-year storage virtualization project, CS3 has deployed virtualization and thin provisioning in its test and development environment. The company has found that this approach has allowed it to reclaim substantial storage space (approximately 40TB) and avoid the purchase of an entire array, saving several hundred thousands of dollars. Despite the initial disruption of migrating to a virtualized environment, the company is seeing substantial payback in terms of better utilization and much simpler change management. ------- Perceived advantages
Perceived drawbacks
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