Moderator: David Vellante
Analyst: David Floyer
After nine years of experience with installing, managing and exploiting SAN infrastructure, the IT industry is entering a new phase of storage and server consolidation. Unlike previous phases, which emphasized better physical allocation of resources (e.g., EMC big-box consolidations of the 1990s) and physical any-to-any connectivity, (e.g., fabric-based SANs of the 2000s) this next era will focus on consolidation of virtual server and storage resources and automated tiered storage strategies.
This means that provisioning new storage controller capacity and moving data across arrays will occur without disrupting application availability, creating the infrastructure to support automated, policy-based movement of data volumes across storage tiers. This is a major focus for users, for whom the inability to move data volumes across arrays without interrupting service levels of high-performance, often transactional applications, is a major block to the adoption of the much-promised tiered-storage architecture.
In addition to providing improved efficiencies, which include reducing costs of up to $50,000 for migrating to new arrays and compliance-driven consolidation of business processes that currently reside on different systems, three main factors are driving new consolidations of block-based SANs:
- Time to provision new servers and storage capacity remains onerous particularly for users with substantial capacity coming off leases needing to migrate to new arrays. Customers report provisioning windows extending from weeks to several months.
- Consolidation promises opportunity to improve customer service levels by automating the provisioning of capacity, reallocation of resources and responses to failures.
- High-quality server and storage virtualization technologies – including server virtualization from VMware, IBM and many others for servers and, on the storage side, IBM’s SAN Volume Controller (SVC), Hitachi’s USP, EMC’s Invista and a broad range of other new storage products – have emerged
This new era has many challenges, starting with financial considerations. In pre-SAN days when DAS ruled, storage utilization was routinely in the 20% range. SANs have at least doubled this metric and provided substantial management benefits, easily offsetting the incremental costs of switches and more expensive software. Consolidation 2.0 promises better utilization but not nearly the 100% improvement seen with the SAN introduction. Users should expect utilization to increase from its current 40%-50% to 60%-70% but not much higher, even with thin provisioning.
Further compounding the challenge of Consolidation 2.0 is the requirement for storage virtualization and great desirability of server virtualization to support much of the automation that provides the basic financial value. This brings a conundrum that while organizations are under extreme pressure to cut costs and improve service levels, virtualization will probably bring with it substantial overhead, increased complexity and require new skill sets. Users must be careful to apply virtualization in small chunks, testing performance, documenting procedural changes, managing software complexity, and getting rid of legacy assets.
Wikibon users consolidating SAN islands suggest the following best practices:
- Virtualize server and storage sides in parallel and consider technology alternatives. VMware for Windows has the early momentum on the server as does IBM’s SVC in storage, but alternatives from several other server and storage suppliers – including EMC, Hitachi, IBM, Sun and upstarts like 3Par – are also available.
- Keep consolidation simple to minimize tiers: Set service-level requirements for applications to include on Tier 1 and allocate everything else to Tier 2 to reduce costs and avoid unnecessary software license expenses. Use Tier 3 for archiving as necessary and as technologies like virtual tape evolve.
- Virtualize everything on Tier 2, but test and retest to be sure application behavior is predictable.
- Create a single SAN environment so there are no constrains to migrating storage to the best array for the job.
The goal of consolidation should be simplification, which will concentrate both vendor and organizational power in fewer hands. This presents pricing and negotiation challenges for users that can be managed over time. Getting this consolidated infrastructure to work properly should be the near-term priority. To avoid long-term dependencies on a single storage supplier, users should establish independent rules, roles, responsibilities and data structures that can accommodate continuous negotiations and multiple storage virtualization strategies over time.
Action Item: IT in general and storage administrations in particular must prepare for lots of changes in the data center as virtual server and storage technologies align and integrate. To prepare for the next phase of storage consolidation, users should simplify block-based SAN strategies by choosing a single storage virtualization approach, minimizing storage tiers and standardizing on a single software management suite for their initial implementations.
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