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A method to expand SSD cache using hot spare disks

IP.com Disclosure Number: IPCOM000233970D
Publication Date: 2014-Jan-06
Document File: 3 page(s) / 49K

Publishing Venue

The IP.com Prior Art Database

Abstract

The invension provides a method for expending SSD cache by assigning all the SSD hot spare disks in the storage system to work as cache memory. SSD hot spare disks are configured to protect raid array in case of disk failure. Use these hot spare disks as SSD cache will enlarge the cache memory capacity, and thus enhance the IO performance. The invension also provides a method for the SSD hot spare disks quit from cache memory, and back to serve as a hot spare disks.

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A method to expand SSD cache using hot spare disks

Solid State Disk (SSD), as a new technology, has been more and more introduced into storage subsystem because of its many advantages, such as the compact size, low power consumption and especially the higher performance than mechanical Hard Disk Drive (HDD). But the cost of SSD is still much higher than mechanical disks.

So a typical way is to compose a hybrid storage subsystem using HDD and SSD together. Part of the SSD will be configured as storage space to store key application and data, and another part of the SSD will be configured as cache memory for the HDD. As

a storage space, usually raid array is used for data redundancy and performance improvement, and hot spare disks are configured in case of disk failure. Figure 1 illustrates this typical hybrid storage subsystem.

Figure 1 A typical Hybrid Storage Subsystem

Due to the fact that cache performance depends mainly on the cache size assuming everything else being the same , there is a desire to maximize the amount of SSD cache memory in the hybrid storage system.

And as the SSD manufacture technology improves, capacity of single SSD disk is greatly enlarged, from GB to TB. So SSD hot spare disks, which are standby in the storage subsystem most of the time, will cause a big waste of user's investment.

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So, use the SSD hot spare disks to expand the SSD cache memory will enlarge the cache memory, thus improve the IO performance, and increase the resource utilization rate. After configuring the SSD hot spare disks as SSD cache memory, th...