Method, device and computer-readable medium for establishing multi-level flash cache using spare disk

Abstract

Embodiments of the present disclosure provide a method, device and computer-readable medium for establishing a multi-level flash cache using a spare disk. In some embodiments, a computer-implemented method is provided. The method includes: in response to receiving an I / O request, determining whether there is a free page in the primary cache in the cache. In response to determining that there is no free page in the primary cache, selecting at least A spare disk to create the secondary cache. Flushing data in the cold pages in the primary cache whose access frequency is lower than a predetermined threshold to the secondary cache. Writing the data involved in the I / O request from the persistent storage device to the cold page.

Description

technical field [0001] Embodiments of the present disclosure relate generally to data storage and, more particularly, to a method, apparatus, and computer-readable medium for establishing a multi-level flash cache using spare disks. Background technique [0002] In disk arrays, there are generally two types of caches in the block layer, namely dynamic random access memory (DRAM) caches and solid state disk (SSD) caches. DRAM cache has the fastest response speed for data requests, but is limited in terms of cost and cache capacity. The response speed of SSD cache to data requests is second only to DRAM cache and SSD cache has relatively lower cost and higher cache capacity to varying degrees compared with DRAM. HDD disks are typically used to store all user data and they respond to I / O requests that cannot be served by DRAM caches and SSD caches. HDD disks have the slowest response time, open capacity, and lowest cost per GB. [0003] In existing products, the hard disk ma...

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Problems solved by technology

For some types of expensive SSD disks, this situation is very wasteful

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