RAID recovery research

In July 2014 we did an analysis of telemetry data obtained during the first half of 2014 with about 15000 RAID recoveries to collect various RAID recovery characteristics. Being software developers for data recovery in general and RAID recovery in particular, we are keenly aware that, on the one hand, our task is to help a client to recover data successfully, but on the other hand, it is very important the recovery is done in a reasonable time. That's why we decided to do this research aimed to reveal how long does it usually take to recover a RAID. During the research other interesting characteristics associated with RAID recovery such as the number of disks in the original array and distribution of RAID layouts among all the recovery cases were found.

Recovery time

Our research revealed that 79% RAID0 can be successfully recovered within an hour, 100% RAID0 recoveries are complete in 48 hours.

Only 20% RAID5 recoveries can be complete within an hour, it takes 48 hours to complete 93% of all the RAID5 recovery cases.

Such results can be explained by two factors: on the one hand, RAID5 is more complex than RAID0 requires the recovery of additional RAID parameters, on the other hand, RAID5 arrays usually have more disks than RAID0 arrays, affecting the speed of the recovery.

Time spent on recovery

RAID levels involved

Our research revealed that all the RAID recovery cases equally affect RAID0 (48%) and RAID5 (48%); the remaining 4% are RAID10 and RAID6 combined.

Number of disks in RAID

Research shown that 90% RAID0 arrays involved in recovery consist of two disks. 81% RAID5 recovery cases are represented by the configurations containing three (33%) or four (48%) disks; the remaining 19% have more than three disks.

Number of disks in array