When Advanced Reconstruction is on, the system monitors the performance of each disk in the array and compares it to the performance of other disks in the same array. Thus the system detects 1, 2 or 3 slowest disks for RAID 5, RAID 6, RAID 7.3 respectively. To keep array performance stable, the system excludes slow disks from reading operations for 5 seconds and calculates the data from the checksums. When the system detects the same disk several times like slow it marks it as "Slow drive" and excludes it from reading operations on the permanent manner.
To heal long-tail latency Advanced Reconstruction skips data blocks when irregular latency occurs during full-stripe reading even from well-operating disks.
Skipped data recovers from RAID checksums. Due to the proprietary RAID engine, checksum calculations takes less time than common read operations from an average physical drive. Therefore, total array performance stays high and stable.