From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ram Ramesh Subject: Why can't I re-add my drive after partition shrink? Date: Thu, 13 Jul 2017 18:17:03 -0500 Message-ID: <2ea5ed99-05b5-25d2-c9d4-8ce1f4945eaa@gmail.com> 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: Linux Raid List-Id: linux-raid.ids I am trying to shring my mdadm underlying disks/partitions as a way of reclaiming space after md shrink operation. Here is my md > Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] > [raid4] [raid10] > md0 : active raid6 sdb1[6] sdg1[11] sdd1[12] sdf1[8] sde1[9] sdc1[10] > 12348030976 blocks super 1.2 level 6, 64k chunk, algorithm 2 > [6/6] [UUUUUU] > bitmap: 2/23 pages [8KB], 65536KB chunk > > unused devices: Here is my mdadm detail about /dev/sdb1 > Avail Dev Size : 11720780943 (5588.90 GiB 6001.04 GB) > Array Size : 12348030976 (11776.00 GiB 12644.38 GB) > Used Dev Size : 6174015488 (2944.00 GiB 3161.10 GB) I fail, remove and repartition /dev/sdb1 so that new partition table looks like this. (No change to data obviously) > New partition table: > Number Start (sector) End (sector) Size Code Name > 1 2048 6442452991 3.0 TiB FD00 Linux RAID > 2 6442452992 11721045134 2.5 TiB FD00 Linux RAID Since new /dev/sdb1 is significantly bigger than what mdadm says that it is using, I thought I could simply re-add the drive. However, I get > sudo mdadm /dev/md0 --re-add /dev/sdb1 > ***mdadm: --re-add for /dev/sdb1 to /dev/md0 is not possible*** Why? What did I miss here? Is it possible to fix this so that I can repartition other drives and -re-add them without having to go through full rebuild after each change? I researched as much as I could on the net and came up with nothing except some one saying that mdadm keeps something at the end of the disk regardless of what it says about "Used Dev Size." Is it possible to move this info so that I could re-add? Ramesh