Write spike performance enhancement in hybrid storage systems

摘要

A hybrid storage array one using two or more storage device tiers. In one implementation, two tiers may be provided by solid state drives (SSDs) and hard disk drives (HDDs). Host application access patterns of a certain type determined to be relatively slow, such as random writes, are detected. The random writes are collected and written to a special reserve space, such as a portion of the SSD storage tier, referred to as a write cache extension. The write cache extension absorbs such accesses that would otherwise be written to HDD storage directly. Data structures are created in a cache memory local to an array controller representing the location on SSD reserve space to which the writes were committed and a location in the storage system where they were originally intended to go. The write cache extension can be enabled all of the time, or only when the array controller write cache experiences certain operating conditions, such as when its utilization exceeds a certain predetermined amount. The approach improves the overall performance of the hybrid array.

主权项

1. An information handling apparatus comprising:
a tier-0 storage portion; a tier-1 storage portion having a device access time that is slower than a device access time of the tier-0 storage portion; a write cache extension portion having a device access time that is faster than a device access time of the tier-1 storage portion; a storage cache main portion; and a storage array controller that:
receives a storage command for access to a page of data;assigns one of a plurality of frequency zones of read and/or write requests to the page of data;if the page is in a higher frequency zone, cache the data in the storage cache main portion;if the page is in a middle frequency zone, migrate the page to the tier-0 storage portion;detects if the storage command is one of a series of random writes to the tier-1 storage portion, and if so, sequentially write the series of random writes to a block of the write cache extension portion, and subsequently write the block to the tier-1 storage portion when the block has reached a particular size.