That completely depends on the RAID controller/software. Smarter ones, with sufficient slots will leave the "failing" drive online long enough to assure that s

That completely depends on the RAID controller/software. Smarter ones, with sufficient slots will leave the "failing" drive online long enough to assure that should a sector fail to be read from the remaining drives an attempt can be made to read it from the "Bad" drive as well. In cases where the drive is being kicked for excessive SMART relocation, or hard read errors this could be the diff between the array going offline and the rebuild succeeding. For something like mdadm, you can simulate this by upgrading /reshaping from RAID5 to RAID6 (or similar) and then pulling the failing drive and reshaping back to raid5. Or as did a few times a decade+ ago when we had a really bad batch of drives, pick the bad sector off the failed drive, compute the corrected sector "by hand" and write it back to the drive with a read error.