Five nines or 99.999% availability standard (5.26 mins downtime per year) has its origins in the telecom industry. It characterizes the technical capabilities of an individual system. It does not characterize the capability of an organization to use the technology to meet its goals. To measure the impact of technology on an organization requires consideration of the entire IT environment and its effectiveness as a whole in providing access to data.

Dell Compellent: Going beyond five nines

By virtualizing physical resources, Dell Compellent Storage Center achieves a higher level of abstraction that overcomes the limitations of traditional storage, allowing you to perform routine management and maintenance without taking down the applications users rely on to keep business moving.

At Dell, we’re addressing data accessibility issues with a 24×7x365 mentality. The Dell Compellent family offers 99.999% availability1 by the standard measure, but we go beyond the concept of five nines. We take planned data downtime into consideration in our approach to building our hardware, the technologies behind our software and in our unique, award-winning support.

Building high availability into hardware

The foundation of continuous data availability is based on a hardware environment in which users can access the data during activities that traditionally require downtime, both unplanned and planned.
Dell removes the potential for a single point of failure from the whole environment rather than merely moving that single point of failure around within the environment. Our approach is to provide a hardware environment in which accessing data uses no shared components.

Clustering dual storage controllers with no shared backplanes or midplanes, and then connecting that fully redundant cluster to storage devices in a multi-loop or multi-chain configuration, provides redundancy at all points and allows for a hardware environment that is highly available. Providing reliability and redundancy in components most likely to fail—power supplies, fans, spinning disk drives—contributes to this infrastructure of availability. Wherever possible, components are designed to be hot swappable, eliminating downtime for maintenance and repair.

Data management traditionally requires planned downtime. Virtualization can help change that. Dell Compellent virtualizes storage at the drive level, enabling you to create high performance, highly efficient virtual volumes in seconds, without allocating drives to specific servers and without complicated capacity planning and performance tuning. Read/write operations are spread across all drives in your virtualized pool of storage, so multiple requests are processed in parallel, accelerating data access.

In addition, you can change and scale your virtualized storage dynamically without disruption or downtime. Start with a single controller, add a second controller, join the two into a cluster, all while allowing access to the data. Add drives and drive enclosures, replace fans and power supplies—even go inside a controller and replace interface cards to upgrade or fix hardware issues, with your data accessible to users all the while.

A hardware environment built on this blueprint can keep data accessible during activities that traditionally had a negative impact on business, and keep the organization moving forward.

Building high availability into software Software

that contributes to data availability includes automated data placement, virtualization, and data protection solutions. Again, the Dell Compellent approach is holistic, and focused on keeping data optimally accessible for users—in any circumstance, and at every stage in its lifecycle.

Dell Compellent storage software features built-in automation that optimizes the provisioning, placement and protection of data throughout its lifecycle. For example, storage tiering enables an organization to keep data available cost effectively. Data Progression, Dell Compellent’s patented tiering technology, automatically classifies and migrates data to the optimum storage tier and RAID level based on actual usage. As shown below, all new data is written to Tier 1, RAID 10 and snapshots cascade to the lowest available tier within 24 hours. Then, the most active blocks of data remain on high-performance drives, while less active blocks automatically move to lower-cost, high-capacity drives. Under this approach, your storage is optimally utilized, data is easily recoverable and users and applications have fast access to the data they need.

Dell Compellent automated tiered storage dynamically classifies and migrates data to the optimum tier based on frequency of access.

Another way Dell Compellent builds high availability into storage software is Dell Compellent Data Instant Replay, sometimes referred to in the industry as “snapshot technology” or “continuous data protection.” A Replay is similar to a snapshot in that it captures a point-in-time copy of data; however, it has intelligence that lets you access read-only data without having to make a copy of that data. You can take continuous, space-efficient snapshots to speed local recovery of lost or deleted files. Once an initial snapshot of a volume is taken, only incremental changes in the data need to be captured. Every Replay is a readable and writable volume that is automatically stored on lower-cost drives, and can be used to recover any size volume to any server in less than 10 seconds.

Remote Instant Replay leverages Replays between local and remote sites for cost-effective disaster recovery and business continuity solutions. After initial site synchronization, only incremental changes in data are replicated on an ongoing basis, cutting hardware, bandwidth and administration costs. You can replicate over Fibre Channel or native IP as your business requires.

Dell Compellent Live Volume, enables dynamic business continuity by letting you move storage volumes between Dell Compellent arrays on demand. All migration occurs transparently while applications remain online. Live Volume functionality is fully integrated in the Dell Compellent platform and requires no additional hardware, server agents or costly appliances. It supports any virtualized server environment and complements leading virtual machine movement engines.