From mboxrd@z Thu Jan 1 00:00:00 1970 From: yizhan Subject: Re: md127 auto created when use "-B" to build a legacy array without superblocks Date: Wed, 27 Jan 2016 17:18:59 +0800 Message-ID: <56A88B83.7040609@redhat.com> References: <597548646.22274436.1441628869039.JavaMail.zimbra@redhat.com> <87k2r5iu0t.fsf@notabene.neil.brown.name> <56A72D21.20707@redhat.com> <87y4bc2e2m.fsf@notabene.neil.brown.name> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <87y4bc2e2m.fsf@notabene.neil.brown.name> Sender: linux-raid-owner@vger.kernel.org To: NeilBrown Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On 01/27/2016 06:03 AM, NeilBrown wrote: > On Tue, Jan 26 2016, yizhan wrote: > >> On 10/02/2015 03:55 PM, Neil Brown wrote: >>> Yi Zhang writes: >>> >>>> Hi Neil >>>> >>>> When testing 00raid1, found the md127 auto created when use "-B" to build a legacy array without superblocks, is it reasonable? >>> This happens because udev notices a new device has appeared, looks >>> inside it, sees that it could be part of an md array, and so runs >>> "mdadm --incremental" on it. >> Hi Neil >> I tried the mdadm --incremental, but it doesn't work, below is the >> operation. >> # mdadm -D /dev/md0 >> /dev/md0: >> Version : >> Creation Time : Tue Jan 26 03:16:17 2016 >> Raid Level : raid1 >> Array Size : 2097152 (2.00 GiB 2.15 GB) >> Used Dev Size : 2097152 (2.00 GiB 2.15 GB) >> Raid Devices : 2 >> Total Devices : 2 >> >> State : clean >> Active Devices : 2 >> Working Devices : 2 >> Failed Devices : 0 >> Spare Devices : 0 >> >> Number Major Minor RaidDevice State >> 0 7 0 0 active sync /dev/loop0 >> 1 7 1 1 active sync /dev/loop1 >> # mdadm -D /dev/md127 >> /dev/md127: >> Version : 1.2 >> Raid Level : raid0 >> Total Devices : 1 >> Persistence : Superblock is persistent >> >> State : inactive >> >> Name : 0 >> UUID : 13ada118:129135ff:686de7b7:4cb71d6d >> Events : 17 >> >> Number Major Minor RaidDevice >> >> - 9 0 - /dev/md0 >> # mdadm -I /dev/md127 >> mdadm: /dev/md127 is not part of an md array. >> # mdadm -I /dev/md0 >> mdadm: cannot reopen /dev/md0: Device or resource busy. >> >> After I stopped md127, the md0 can be used again. > If, after stopping md127, you try > > mdadm -I /dev/md0 > > again it will start /dev/md127 again. This is what udev does which > causes md127 to appear in the first place. > > NeilBrown Thanks Neil I have tried 'mdadm -I /dev/md0', the /dev/md127 start again Yi > >> Thanks >> Yi >>> Sometimes we want udev to do that. Sometimes we don't. >>> There is no easy way for udev to know what we want. >>> >>> NeilBrown >>> >>> >>>> pls check below detailed info: >>>> >>>> + mdadm -CR /dev/md0 --level=raid1 -n3 /dev/loop0 /dev/loop1 /dev/loop2 >>>> mdadm: /dev/loop0 appears to contain an ext2fs file system >>>> size=58368K mtime=Thu Jan 1 08:00:00 1970 >>>> mdadm: Note: this array has metadata at the start and >>>> may not be suitable as a boot device. If you plan to >>>> store '/boot' on this device please ensure that >>>> your boot-loader understands md/v1.x metadata, or use >>>> --metadata=0.90 >>>> mdadm: /dev/loop1 appears to contain an ext2fs file system >>>> size=38912K mtime=Thu Jan 1 08:00:00 1970 >>>> mdadm: Defaulting to version 1.2 metadata >>>> mdadm: array /dev/md0 started. >>>> + mdadm --wait /dev/md0 >>>> + cat /proc/mdstat >>>> Personalities : [raid6] [raid5] [raid4] [raid1] >>>> md0 : active raid1 loop2[2] loop1[1] loop0[0] >>>> 19968 blocks super 1.2 [3/3] [UUU] >>>> >>>> unused devices: >>>> + mdadm -S /dev/md0 >>>> mdadm: stopped /dev/md0 >>>> + mdadm -B /dev/md0 -l raid1 -n2 /dev/loop0 /dev/loop1 >>>> mdadm: array /dev/md0 built and started. >>>> + sleep 2 >>>> + cat /proc/mdstat >>>> Personalities : [raid6] [raid5] [raid4] [raid1] >>>> md127 : inactive md0[0](S) >>>> 19968 blocks super 1.2 >>>> >>>> md0 : active raid1 loop1[1] loop0[0] >>>> 20000 blocks super non-persistent [2/2] [UU] >>>> >>>> unused devices: >>>> [root@dhcp-12-171 bug]# uname -r >>>> 4.2.0 >>>> [root@dhcp-12-171 bug]# mdadm -D /dev/md0 >>>> /dev/md0: >>>> Version : >>>> Creation Time : Mon Sep 7 20:21:20 2015 >>>> Raid Level : raid1 >>>> Array Size : 20000 (19.53 MiB 20.48 MB) >>>> Used Dev Size : 20000 (19.53 MiB 20.48 MB) >>>> Raid Devices : 2 >>>> Total Devices : 2 >>>> >>>> State : clean >>>> Active Devices : 2 >>>> Working Devices : 2 >>>> Failed Devices : 0 >>>> Spare Devices : 0 >>>> >>>> Number Major Minor RaidDevice State >>>> 0 7 0 0 active sync /dev/loop0 >>>> 1 7 1 1 active sync /dev/loop1 >>>> [root@dhcp-12-171 bug]# mdadm -D /dev/md127 >>>> /dev/md127: >>>> Version : 1.2 >>>> Raid Level : raid0 >>>> Total Devices : 1 >>>> Persistence : Superblock is persistent >>>> >>>> State : inactive >>>> >>>> Name : dhcp-12-171.nay.redhat.com:0 (local to host dhcp-12-171.nay.redhat.com) >>>> UUID : 40ace956:a9dd0793:f4984d2b:8431b92b >>>> Events : 17 >>>> >>>> Number Major Minor RaidDevice >>>> >>>> - 9 0 - /dev/md0 >>>> >>>> Best Regards, >>>> Yi Zhang