Home  |  Solutions  |  Tiered Storage
Hybrid Data Storage Solution with SSD and HDD Tiers

Dot Hill’s tiered data storage solution, the AssuredSAN Pro 5000, automatically manages ‘hot’ and ‘cold’ data in real-time to deliver storage performance when you need it most. With this remarkable tiered data storage solution (and SAN), powered by RealStor™ technology, your storage responds minute by minute to changes in data requirements, moving the most heavily accessed data up to the SSD tier, while detecting less active data and moving it to a lower tier. This data migration happens in real-time, without policy setting and human intervention.

Data Storage Tiering and Application Performance

The performance of virtually every application is limited by the relatively slow input and output (I/O) to disk storage. A common way to mitigate this limitation and improve performance is to replicate active data from disks to higher-speed memory. This can be accomplished either through cache in servers or storage, or through automated tiered storage solutions.

Boosting Performance with SSD’s

Advances in technologies have created a new layer or tier of storage between cache memory and traditional hard disk drives: the solid-state drive or SSD. SSDs use flash memory, similar to the high-speed memory that is used for caching, but on the scale of a hard disk drive (HDD). SSDs can be used either to create a very large cache or a very fast full tier of disk storage. Either way, the performance gains can be significant for virtually any application. The Pro 5000 Series offers options for expanded read cache as well as an expanded SSD tier. Just think what that can mean for Microsoft Exchange or your VMware environement. The Evaluator Group has published two Solution Briefs on the benefits of tiered storage for Microsoft Exchange and VMware.

SSD Tiers – Response in 10 Nanoseconds versus 10 milliseconds

Consider this: accessing data in the server’s memory takes only 10 nanoseconds, while accessing data on a hard disk drive takes about 10 milliseconds—a difference of 1,000,000 times or six orders of magnitude. In between is solid state storage using flash memory with an I/O of 3 to 5 microseconds—2000 to 3000 times faster than with HDDs.

Storage Tiering – Balancing Cost and Performance

The advantage of data storage tiering is that it offers an effective balance of high performance (with the very fast SSDs) and low cost (with the relatively inexpensive HDDs). In the future when the cost of SSDs approaches the cost of HDDs on a per-byte basis, it may be feasible to deploy a purely SSD-based SAN. But that day is a long way away, which makes data storage tiering the most cost-effective way of achieving significant performance gains today.

Autonomic Real-time Tiering and Migration

Dot Hill’s RealStor technology overcomes the two major limitations found in most tiered storage systems today by automating the migration of data in real-time. The system virtualizes both the SSDs and HDDs at the sub-LUN level using 4 MB pages distributed across multiple RAID sets. Intelligent RealStor algorithms then continuously monitor I/O access patterns and automatically move Hot Data to the SSDs to maximize the speed of I/O operations and, therefore, improve performance of the aggregate application workload.

RealStor technology is found in the AssuredSAN Pro 5000tiered storage solution, Dot Hill’s midrange storage system – offering real-time tiering, thin provisioning, and rapid RAID rebuild, all with a simple and intuitive web user interface.

For more technical information on how RealStor works and improves application performance, download the RealStor White Paper.