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: Tue, 26 Jan 2016 16:24:01 +0800 Message-ID: <56A72D21.20707@redhat.com> References: <597548646.22274436.1441628869039.JavaMail.zimbra@redhat.com> <87k2r5iu0t.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: <87k2r5iu0t.fsf@notabene.neil.brown.name> Sender: linux-raid-owner@vger.kernel.org To: Neil Brown Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids 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. 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