Hybrid array

A hybrid array is a form of hierarchical storage management that combines hard disk drives (HDDs) with solid-state drives (SSDs) for I/O speed improvements.

Hybrid storage arrays aim to mitigate the ever increasing price-performance gap between HDDs and DRAM by adding a non-volatile flash level to the memory hierarchy.^[1] Hybrid arrays thus aim to lower the cost per I/O, compared to using only SSDs for storage. Hybrid architectures can be as simple as involving a single SSD cache for desktop or laptop computers, or can be more complex as configurations for data centers and cloud computing.

Implementations

Some commercial products for building hybrid arrays include:

• Adaptec demonstrated the MaxIQ series in 2009.^[2]
• Apple's Fusion Drive
• Linux software includes bcache, dm-cache, and Flashcache (and its fork EnhanceIO).
• Condusive's ExpressCache is marketed for laptops.
• EMC Corporation VFcache was announced in 2012.^[3][4]
• Fusion-io acquired ioTurbine in 2011,^[5] and the product line it acquired by buying NexGen in 2013.^[6]
• Hitachi Accelerated Flash Storage (HAFS) used together with the Hitachi Dynamic Tiering software^[7]
• IBM Flash Cache Storage Accelerator (FCSA) server software^[8]
• Intel's Smart Response Technology for desktop
• Intel's Cache Acceleration Software for servers and workstations
• LSI CacheCade software for their controllers^[9]
• Marvell's HyperDuo controllers^[10]
• Microsoft's Automated Tiering (since Windows 2012 R2)
• NetApp's Flash Cache, Flash Pool, Flash Accel^[11]
• Oracle Corporation markets products such as Exadata Smart Cache Flash, and the FS1 flash storage system.^[12]
• Microsoft ReadyBoost allows personal computers to use USB flash drives (or any solid-state media) as cache.
• Nvelo DataPlex SSD caching software was announced in 2011,^[13] and was acquired by Samsung in 2012.^[14]
• SanDisk FlashSoft for Windows, Linux, and vSphere^[5]
• Products are offered by vendors like AMI StorTrends,^[15] Tegile Systems, Reduxio, and Tintri.^[16]
• ZFS using hybrid storage pools, are used for example in some Oracle Corporation products.^[17]

See also

• Hybrid drive – built-in flash cache, handled by firmware
• Automated tiered storage – another name for hierarchical storage management
• The "five-minute rule" for caching