Data reading method, RAID controller and storage device

Abstract

The invention relates to the field of storage, in particular to a data reading method, an RAID controller and a storage device. The method comprises the steps of receiving an IO reading request sent by a host; determining intervals in an interval set which the IO reading request belongs to according to the size of the IO reading request, wherein the interval set comprises at least two intervals, and each interval in the interval set corresponds to a target time delay threshold; adjusting the target time delay thresholds of the intervals in the interval set according to a preset threshold adjustment policy every a preset first cycle; monitoring a time delay value of the IO reading request during return; and when it is determined that the time delay value of the IO reading request exceeds the target time delay threshold, performing degradation reading operation on the IO reading request. According to the method, an average time delay of a system can be effectively shortened, the QoS of an RAID adopting the method can be improved, and the RAID performance of an SSD is utilized to the maximum extent, so that the IO performance of the RAID is improved.

Description

technical field [0001] The invention relates to the storage field, in particular to a data reading method, a RAID controller and a storage device. Background technique [0002] With the rapid development of solid state drive (Solid State Drives, SSD) technology, the storage capacity of the SSD is getting larger and the reading and writing speed is getting faster and faster, and its application range is getting wider and wider. However, as the erasing times of SSD particles increase, especially when the flash memory chip NAND Flash is about to reach the upper limit of its wear value, a small amount of input and output (Input Output, IO) has to go through multiple read retries or use Only other processing measures in the SSD can read the correct data. At this time, the delay of reading IO will be much larger than that of normal reading IO. In addition, as the number of erasing and writing of particles increases, the overall performance of the SSD will gradually deteriorate. In...

AI Technical Summary

Problems solved by technology

[0005] However, the existing method of keeping the delay value constant during operation does not take into account other influencing factors, such as changes in the IO delay distribution caused by changes in the ratio of read and write IOs and the size distribution of IOs. , this change usually leads to a large change in the delay value of IO. Therefore, whether it is a disk array composed of mechanical hard disks or a disk array composed of SSDs, a fixed delay threshold cannot well limit the timeout IO to reduce the overall The level of read IO delay; in addition, for a disk array composed of SSDs, since the delay value is fixed, in the case of a fixed delay value, for a slow IO, the delay value of slow IO completion is not It is not necessarily slower than the delay value of the slow IO downgraded read completion, so the effect of reducing the average delay of the system by downgrading the slow IO does not always exist; in addition, the 4KB random read rate of the SSD is very high, and the IO request Generally, they are also at the KB level. Therefore, in a disk array composed of SSDs, the degraded reading of some IOs will not have a significant impact on the performance of other SSDs in the disk array. Therefore, the method of fixing the delay threshold Does not work well in disk arrays composed of SSDs

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