From mboxrd@z Thu Jan 1 00:00:00 1970 From: Killian De Volder Subject: Unable to reduce raid size. Date: Fri, 18 Jul 2014 10:50:54 +0200 Message-ID: <53C8DFEE.7000000@megasoft.be> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Hello, I have a strange issue, I cannot reduce the size of a degraded raid 5: strace mdadm -vv --grow /dev/md125 --size=2778726400 Fails with: Stace: open("/sys/block/md125/md/dev-sdb4/size", O_WRONLY) = 4 write(4, "2778726400", 10) = -1 EBUSY (Device or resource busy) close(4) Stdout: component size of /dev/md125 unchanged at 2858285568K Stderr: Any suggestions ? Note: I can work around this bug, by moving partitions around a bit, and not requiring the size reduction. However I suspect a bug/undocumented border case that should be resolved? Things I tried: --------------- - Disable bcache udev rules (as it was appearing in each attempt, maybe it got triggered during resize, seems not to be the case). - I have tried the same with loop files -> this works fine even with bcache (and the udev rules disabled) - Removed the internal write bitmap - Opend the file os.open("md125",os.O_EXCL,os.O_RDWR) in Python to test if it's in use somewhere (command worked fine) - Set array-size to the less then the desired new size (while still not destroying the FS below it). Information: ------------ Kernel version: 3.15.5 mdadm tools: 3.3-r2 mdadm --detail: /dev/md125: Version : 1.2 Creation Time : Wed Apr 16 20:58:09 2014 Raid Level : raid5 Array Size : 8283750400 (7900.00 GiB 8482.56 GB) Used Dev Size : 2858285568 (2725.87 GiB 2926.88 GB) Raid Devices : 4 Total Devices : 3 Persistence : Superblock is persistent Update Time : Fri Jul 18 09:53:08 2014 State : clean, degraded Active Devices : 3 Working Devices : 3 Failed Devices : 0 Spare Devices : 0 Layout : left-symmetric Chunk Size : 512K UUID : 885c588b:c3503d9d:c67b86db:2887f8f7 Events : 6440 Number Major Minor RaidDevice State 0 8 36 0 active sync /dev/sdc4 2 0 0 2 removed 2 8 20 2 active sync /dev/sdb4 4 8 52 3 active sync /dev/sdd4 -- Killian De Volder Megasoft bvba killian.de.volder@megasoft.be