Automated Tiered Storage Gaining Traction Through Cost Savings, Performance

Automated tiered storage has become a nearly ubiquitous feature in the industry thanks to its perceived benefit of being able to move a company's data to different types of storage media based on the value of the data and the cost of the storage.

Most major storage vendors offer their own slightly-different take on automatic tiered storage either as an option or as an included feature, and they say uptake of the feature among customers is strong.

However, the feature is not without its detractors, with other storage capacity management solutions falling storage media prices providing alternatives to customers and their solution providers.

Automated tiered storage, or dynamic tiering, is the ability of a storage device to automatically migrate data from one type of media to another based on how "hot," or frequently accessed, the data is and on the cost of the different types of media.

With automated tiered storage, data which is frequently accessed by an application should be sitting on the fastest available media so that it can be read or updated quickly. As that data ages, or becomes less frequently accessed, it can be migrated to slower hard disk drives or eventually to tape or a storage cloud where the cost of storing it is much lower. However, that data can also be migrated back to higher-speed media if access to it increases.

The user should not be aware on which tier his or her data is sitting. However, the user may notice a drop in performance when accessing data which has not been accessed for some time.

Dynamic tiering is not a new technology. Originally known as hierarchical storage management, or HSM, it was first developed by IBM to migrate mainframe data between hard drive and tape.

Dynamic tiering takes advantage of the performance vs. cost characteristics of different types of storage media.

Tier 0, which is currently the fastest storage tier, includes solid state drives (SSDs). SSDs get their high performance from the use of high-speed Flash memory instead of spinning discs to store data. In an automated tiered storage environment, frequently accessed data may be kept on SSDs while all other data is moved to other tiers because of the high cost of SSDs.

Tier 1 includes high-speed hard drives, typically those with SAS or Fibre Channel interfaces. Tier 2 typically includes lower-speed SATA hard drives. SAS or Fibre Channel drives feature higher performance than SATA drives, but SATA drives are much less expensive on a per-gigabyte basis and feature much higher capacities.

Tier 3 storage includes low-cost tape and optical disc media. However, their large capacities and slow performance make them useful for backing up or archiving data which is not likely to be accessed for normal business purposes.

There is currently talk around an even higher performance tier of storage based on Flash or DRAM memory in servers which can be used as a cache in front of SSDs to increase the performance of accessing the hottest data.

EMC, for instance, in May unveiled its "Project Lightning," a new PCIe Flash-based server cache to move data closer to the processor. By extending EMC's Fully Automated Storage Tiering (FAST) technology to that cache, it will also serve as a high-performance direct-attach storage device. It is expected to be available later in 2011, and may be part of an automated tiered storage architecture after then.

NEXT: Different Vendors, Different Ways To Tier Storage

Keith Norbie, vice president of sales at Nexus Information Systems, a Minnetonka, Minn.-based solution provider and long-term EMC partner, said that EMC seems to be looking to add a new tier of storage, one that is faster than Tier Zero. "EMC seems to have a strategy to migrate workloads between servers and storage," he said. "Without saying it directly, EMC seems to be saying there is a higher performance level of storage outside the storage controller that's faster than Tier Zero. Maybe it's Tier Minus-One."

Many storage vendors also provide high-performance cache memory on their arrays to hold data as it is read and written, with such data eventually moved to SSD or other tiers. However, since such cache memory is only used to increase performance but not store the data, it is usually not considered part of an automated tiered storage scheme.

Vendors' implementation of automated tiered storage technology varies considerably.

Xiotech's Intelligent Storage Element (ISE), which is a sealed storage blade featuring 14.4 TBs of capacity along with the controller, power supplies, and super capacitors. features both SSDs and hard drives. It also includes the company's Continuous Adaptive Data Placement (CADP), which provides automated movement of data "hot spots" between the SSDs and hard drives based on user-configured thresholds.

Promise Technology is preparing to introduce HyperCache-R, which will automatically load hot data to the higher performance SSD tier based on the access pattern of the data, to its vTrak S3000 appliances.

Oracle offers a couple of automated tiered storage schemes. Its Smart Flash Cache works with its Oracle Database 11g to recognize database-specific I/O patterns and keep the most likely to be used data in flash based storage. The company also offers Hybrid Storage Pools for its Sun ZFS storage appliance for moving data between SSDs and high-capacity hard drives.

Oracle also offers the Sun Storage Archive Manager software for policy-driven automatic migration of data between tiers, and StorageTek Virtual Storage Manager, a feature of its virtual tape library for mainframe environments which migrates data between high-performance disk, high-capacity disk, and tape.

NetApp's Virtual Storage Tier (VST) is a self-managing, data-driven service layer based on the integration of intelligent caching and advanced storage efficiency technology. It provides real-time assessment of workload priorities and optimizes I/O requests for cost and performance to move data to the appropriate tier.

HP P9500 disk array includes ’Smart Tiers’ for sub-LUN tiering and ’AutoLUN’ for LUN-level tiering. For HP's 3PAR products, HP 3PAR Dynamic Optimization Software offers LUN-level tiering while HP 3PAR Adaptive Optimization Software offers sub-LUN tiering.

For BlueArc , automated tiered storage is a feature within its SiliconFS file system, making it available to users at no additional cost.

Hitachi Data Systems offers automated volume-based tiering on its USP, USP V, and Virtual Storage Platform (VSP) appliances. It also offers Hitachi Dynamic Tiering (HDT), a page-based automated tiering, on its VSP appliances.

Dell offers automated tiering in two of its storage platforms.

For Dell Compellent, the company's Data Progression technology intelligently and actively moves data at a granular level between different RAID levels and disk types, and can support servers using various interconnects from iSCSI to FCoE.

Dell EqualLogic iSCSI SAN arrays also offer dynamic tiering within primary storage arrays in its PS6000XVS and PS6010XVS appliances. The company plans new enhancements to the feature later this year.

NEXT: Even More Ways To Tier Storage

SGI's offering, DMF, is a policy-based automated tiering package, and is used to virtualize storage tiers in large active archive environments.

CommVault's Simpana 9 data protection software allows dynamic tiering across all backup and archiving storage tiers, but not for primary storage except to capture recovery copies from hardware snapshots in conjunction with customers' primary storage arrays. Data movement across tiers can be automatically scheduled based on user-defined policy.

Quantum's StorNext storage virtualization software includes Storage Manager, a policy-based data mover that automatically and transparently copies or moves data to another tier of storage.

EMC, the first major storage vendor to make SSD an option for a mainstream storage array, offers Fully Automated Storage Tiering (FAST) across its Symmetrix, VNX, Clariion, and Celerra arrays. FAST supports both block and file/object data types.

Isilon, which last year was acquired by EMC, also offers automated tiering for scale-out NAS via its SmartPools software application.

IBM offers its System Storage Easy Tier automated tiering software with its DS8000, Storwize V7000, and SAN Volume Controller (SVC) storage lines to improve performance. The company also offers automated tiering on its Scale-Out NAS (SONAS) system, where the focus is on reducing cost as part of an information lifecycle management (ILM) approach.

Avere Systems' Tiered File System (TFS) dynamically tiers data by intelligently and automatically moving it between tiers based on demand. It stores active data on the RAM, SSD, and HDD media internal to the company's FXT storage appliances.

Cutting Edge Networked Storage is planning to shortly release a new product, Power Saving Cloud Archive (PSCA), which includes a scale-out NAS for primary storage on SSD, high-performance disk, and large capacity disk, with the ability to move old data to disk which can then be turned off to save power.

About half the vendors offer automated tiered storage as a separately licensed product, while about half offer it with a storage array or storage software at no additional charge.

Solution providers are mixed in terms of the value of automated tiered storage.

Customers are clearly implementing the technology, and will increasingly continue to do so as they understand the benefits and ease-of-use, said Dave Cerniglia, president of Consiliant Technologies, an Irvine, Calif.-based solution provider.

For enterprises, Consiliant sells all the functionality of a storage system including automated tiered storage because of the need for reliability, availability, and serviceability among such customers, Cerniglia said.

"We don't look at it as a line item, but as part of a solution," he said.

In the midrange, however, automated tiered storage still requires long conversations with customers, Cerniglia said. "We still have to explain how it works," he said.

Rolf Strasheim, director of client solutions at Peak UpTime, a Tulsa, Okla.-based solution provider, said that for most customers, the continuing fall in the price of hard disk or SSD storage cancels many of the benefits of automated tiered storage.

Peak UpTime has automated tiered storage offerings through its vendor partners such as NetApp, but for most customers, increasing storage performance is as simple as adding Flash cache memory or an SSD, Strasheim said.

"As the cost of SSDs and high-performance hard drives continue to fall, it's hard to see the value of dynamic tiering," he said. "Customers get 90 percent of the benefit of an SSD just by adding Flash cache, but at a much lower cost.."

Unlike automated tiered storage, which requires customers to configure and tweak parameters, Flash cache is much less complex, Strasheim said. "I like the simple solution," he said. "If it's a choice between Flash cache and auto tiering, I'll choose Flash cache. There's not a lot of care and feeding to do. There's no complex operations, move a little bit of data here, or a little bit of data there."