Good morning everyone. After a discussion on the kernelnewbies IRC channel I'm asking for taking this feature request into consideration. I'd like to see a new mdadm switch --assume-all-dirty or something more suitable used together with the --add switch, that would increase the MD RAID5 rebuild speed in case of rotational drives by avoiding reading and checking the chunk consistency on the newly added drive. It would change the rebuild strategy in such way It would only read from the N-1 drives containing valid data and only write to the newly added 'empty' drive during the rebuild. That would increase the rebuild speed significantly in case the array is full enough so that the parity could be considered inconsistent for most of the chunks. In case of huge arrays (48TB in my case) the array rebuild takes a couple of days with the current approach even when the array is idle and during that time any of the drives could fail causing a fatal data loss. Does it make at least a bit of sense or my understanding and assumptions are wrong? Thank you, Jaromir Capik
