On Sun, 18 Jan 2015 21:33:50 -0500
Xiao Ni [off-list ref] wrote:

----- Original Message -----

quoted

From: "Joe Lawrence" <redacted>
To: "Xiao Ni" <redacted>
Cc: "NeilBrown" <redacted>, linux-raid@vger.kernel.org, "Bill Kuzeja" <redacted>
Sent: Friday, January 16, 2015 11:10:31 PM
Subject: Re: RAID1 removing failed disk returns EBUSY

On Fri, 16 Jan 2015 00:20:12 -0500
Xiao Ni [off-list ref] wrote:

quoted

Hi Joe

   Thanks for reminding me. I didn't do that. Now it can remove
   successfully after writing
"idle" to sync_action.

   I thought wrongly that the patch referenced in this mail is fixed for
   the problem.

So it sounds like even with 3.18 and a new mdadm, this bug still
persists?

-- Joe

--

Hi Joe

   I'm a little confused now. Does the patch 45eaf45dfa4850df16bc2e8e7903d89021137f40 from linux-stable
resolve the problem?

   My environment is:

[root@dhcp-12-133 mdadm]# mdadm --version
mdadm - v3.3.2-18-g93d3bd3 - 18th December 2014  (this is the newest upstream)
[root@dhcp-12-133 mdadm]# uname -r
3.18.2


   My steps are:

[root@dhcp-12-133 mdadm]# lsblk 
sdb                       8:16   0 931.5G  0 disk 
└─sdb1                    8:17   0     5G  0 part 
sdc                       8:32   0 186.3G  0 disk 
sdd                       8:48   0 931.5G  0 disk 
└─sdd1                    8:49   0     5G  0 part 
[root@dhcp-12-133 mdadm]# mdadm -CR /dev/md0 -l1 -n2 /dev/sdb1 /dev/sdd1 --assume-clean
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: Defaulting to version 1.2 metadata
mdadm: array /dev/md0 started.

   Then I unplug the disk.

[root@dhcp-12-133 mdadm]# lsblk 
sdc                       8:32   0 186.3G  0 disk  
sdd                       8:48   0 931.5G  0 disk  
└─sdd1                    8:49   0     5G  0 part  
  └─md0                   9:0    0     5G  0 raid1 
[root@dhcp-12-133 mdadm]# echo faulty > /sys/block/md0/md/dev-sdb1/state 
[root@dhcp-12-133 mdadm]# echo remove > /sys/block/md0/md/dev-sdb1/state 
-bash: echo: write error: Device or resource busy
[root@dhcp-12-133 mdadm]# echo idle > /sys/block/md0/md/sync_action 
[root@dhcp-12-133 mdadm]# echo remove > /sys/block/md0/md/dev-sdb1/state 


   Now after I set idle to sync_action, it can be removed as you said in the mail.
It's a good workaround. Is this OK? 

Best Regards
Xiao

Hi Xiao,

According to my notes, the "idle" sync_action was always a viable
workaround, with or with this change.

Neil's patch should have made it possible to issue only a
"faulty" and "remove" to remove the RAID component.

I don't have an exact version, but it appears that my mdadm version was
an upstream git from Oct 27-th timeframe.

-- Joe

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