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Providing Solid-state Disk Capability in a Storage Controller

IP.com Disclosure Number: IPCOM000019207D
Publication Date: 2003-Sep-04
Document File: 5 page(s) / 42K

Publishing Venue

The IP.com Prior Art Database

Abstract

The present invention is a scalable, networked storage controller that incorporates dynamically reconfigurable cache for the purposes of allocating cache to serve as a solid-state disk (SSD) or as controller cache memory. The cache resides in each storage controller and can be configured on the fly as system requirements for cache vs. SSD space change.

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PROVIDING SOLID-STATE DISK CAPABILITY IN A STORAGE CONTROLLER

Robert Horn and Virgil Wilkins, Aristos Logic Corporation.

27051 Towne Centre Drive, Suite 290, Foothill Ranch, CA 92610

Abstract of the Invention

The present invention is a scalable, networked storage controller that incorporates dynamically reconfigurable cache for the purposes of allocating cache to serve as a solid-state disk (SSD) or as controller cache memory. The cache resides in each storage controller and can be configured on the fly as system requirements for cache vs. SSD space change.

Description of the Invention

The present invention incorporates SSD functionality into storage controllers in a SAN in order to provide 100% cache hit statistics, low latency, and higher inputs/outputs per second (IOPS).

Figure 1) conventional storage controller with SSD architecture

Figure 1 is a diagram of a conventional storage controller with SSD architecture 100. Architecture 100 includes a host 1 110 and a host 2 120 coupled to a SAN fabric 130. Also coupled to SAN fabric 130 are a storage controller 1 140 (with a storage element 145), a storage controller 2 150, and a discrete SSD device 160 and another discrete SSD device 195. SSD device 160 may further include a battery 170, a non-volatile RAM (NVRAM) 180, a disk backup 190.

In operation, data may be transferred from slower non-volatile devices such as storage element 145 to SSD device 160. This data can now be accessed by Host 1 110 or Host 2 120 at speeds of two to three orders of magnitude faster than the data could be accessed from storage element 145.

SSD device 160 acts as a data redundancy storage device only. The system must read stored data from storage element 145, for example, and copy the data to SSD device 160. Therefore, the SSD device 160 is merely a dedicated copy of some permanent storage. Likewise, in another example, host 1 110 may request data stored on storage element 145. Although the data is stored redundantly on SSD device 160, which happens to have a faster access time, storage controller 1 140 fills the request from host 1 110 and sends the requested data through SAN fabric 130. Retrieving the data from storage element 145 is slower than retrieving the redundant data from SSD device 160 because storage element 145 is a mechanical disk drive and has a greater seek time latency. Because the data on SSD device 160 is not the original data, SSD device 160 is not the primary responder to the request; storage element 145 responds instead.

There are several issues associated with conventional architecture 100. Firstly, there is an issue of cost associated with SSD device 160 for the amount of storage provided. The cost per unit of data storage for high-speed semiconductor memory is approximately 500 times the cost for magnetic disk storage.

There is also an issue of data storage reliability associated with architecture 100. It may be very advantageous in certain applications to store primary data onto SSD device...