Block-based storage systems with auto-tiering software that can move chunks of data to the optimal tier at the right time could make solid-state drives (SSDs) a more viable option this year for IT shops that have been reticent to use the performance-boosting technology.
Because SSDs are more expensive than ordinary hard disk drives (HDDs), IT shops typically need to reserve ultra-fast solid-state storage for their most mission-critical applications and I/O-intensive workloads. But manually tiering data can be cumbersome, especially if an application's performance requirements change frequently.
"If you want to run an efficient data center, you have no choice" but to use automated tiering, said Valdis Filks, a research director for storage technologies and strategies at Stamford, Conn.-based Gartner Inc. Filks predicts that automated tiering will become as common in storage systems as virtual memory is in computers. "It's just a natural evolution of the storage hierarchy," he said.
Sub-LUN auto tiering
The latest innovation is sub-LUN auto tiering, which is a step up from the prior approach of migrating an entire LUN or volume. Sub-LUN auto tiering enables the system to shift data at a more granular level, increasing the likelihood that only the most active or performance-sensitive chunks go to SSDs or fast HDDs, such as 15,000 rpm Fibre Channel (FC) or SAS disks.
"I can't tell you how many IT guys told me, 'Over my dead body,'" at the thought of automatically shifting an entire volume from one storage tier to another, said Arun Taneja, founder and consulting analyst at Taneja Group in Hopkinton, Mass.
Compellent Technologies Inc., which pioneered the use of block-level auto tiering in 2005 with its Data Progression software, now has plenty of company. In December 2010, Dell Inc. announced plans to acquire Compellent, just three months after Hewlett-Packard (HP) Co. disclosed its intention to buy 3PAR Inc. and several months after 3PAR launched its Adaptive Optimization auto tiering.
Other prominent block-based sub-LUN auto-tiering offerings include EMC Corp.'s Fully Automated Storage Tiering for Virtual Pools (FAST VP), Hitachi Data Systems' Dynamic Tiering with its Virtual Storage Platform (VSP), and IBM's Easy Tier with its Storwize V7000 and DS8700. IBM plans to support Easy Tier in its DS8800 in the second quarter.
Additional options for auto tiering
Users have additional options for auto tiering. Moving data between arrays from different vendors generally requires a block-based storage virtualization product such as IBM's SAN Volume Controller (SVC), FalconStor Software Inc.'s Network Storage Server (NSS) SAN Accelerator or Hitachi's Universal Storage Platform (USP). File system-based virtualization products include Avere Systems Inc.'s FXT NAS appliances, HP's StorageWorks X9000 and Symantec Corp.'s Storage Foundation.
Cloud storage presents yet another alternative. Cloud gateway options for auto tiering include Cirtas Systems Inc.'s Bluejet Cloud Storage Controller, Nasuni Corp.'s Filer and StorSimple Inc.'s Hybrid Storage Appliance.
But sub-LUN auto tiering has the most momentum in block-based storage systems, as most of the storage heavyweights promote their new and improved offerings in connection with SSDs.