From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eyal Lebedinsky Subject: What does --replace actually do? Date: Fri, 15 Apr 2016 21:26:48 +1000 Message-ID: <5710CFF8.70508@eyal.emu.id.au> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Sender: linux-raid-owner@vger.kernel.org To: list linux-raid List-Id: linux-raid.ids When I request to replace sda with sdj (RAID6 in my case), does it create sdj from the other members (NOT using sda) or does it make a copy of (by reading) sda? I hope it is the former, assuming sda is having issues and the action is precautionary. I see on stackexchange is mentioned that it actually does the latter: http://unix.stackexchange.com/questions/74924/how-to-safely-replace-a-not-yet-failed-disk-in-a-linux-raid5-array And while I am here, can I replace two members at the same time? This should save time as it takes about 10 hours to reconstruct a 4TB member. TIA -- Eyal Lebedinsky (eyal@eyal.emu.id.au)