Adaptive, proactive raid rebuild

A data storage system, comprising:

• a redundant array of inexpensive disks (RAID) controller for a plurality of storage devices configured as a RAID storage array, wherein the RAID controller is configured to perform:
• monitoring the plurality of storage devices in the RAID storage array;
• detecting that a host read request of a host has a latency exceeding a latency threshold;
• based on the monitoring, determining whether a proactive rebuild of data requested by the host read request in absence of a data error would be likely to reduce the data access latency of the host read request, wherein the determining includes determining whether a probability that a rebuild read request will be subject to a random occurrence of high access latency exceeds a probability threshold;
• and
• based on determining that a proactive rebuild of the data requested by the host read request would be likely to reduce the data access latency of the host read request, initiating the proactive rebuild of the data.

A program product, comprising:

• a storage device;
• program code stored on the storage device and executable by a redundant array of inexpensive disks (RAID) controller of a RAID storage array including a plurality of storage devices to cause the RAID controller to perform:
• monitoring the plurality of storage devices in the RAID storage array;
• detecting that a host read request of a host has a latency exceeding a latency threshold;
• based on the monitoring, determining whether a proactive rebuild of data requested by the host read request in absence of a data error would be likely to reduce the data access latency of the host read request, wherein the determining includes determining whether a probability that a rebuild read request will be subject to a random occurrence of high access latency exceeds a probability threshold;
• and
• based on determining that a proactive rebuild of the data requested by the host read request would be likely to reduce the data access latency of the host read request, initiating the proactive rebuild of the data.