From mboxrd@z Thu Jan  1 00:00:00 1970
From: NeilBrown <neilb@suse.de>
Subject: Re: raid5 Unplug the disk
Date: Thu, 5 Feb 2015 16:03:04 +1100
Message-ID: <20150205160304.1119bb06@notabene.brown>
References: <2c82c493-1fd8-4e59-9f9c-ecd2ab4296e3@aliyun.com>
	<CAEhu1-4krpTbF-0mLdgoTKrkdrWo8J2k80BC0t48rv3WkG3UBA@mail.gmail.com>
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To: John Drescher <drescherjm@gmail.com>
Cc: lilofile <lilofile@aliyun.com>, stan <stan@hardwarefreak.com>, Linux RAID <linux-raid@vger.kernel.org>
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On Wed, 28 Jan 2015 11:59:30 -0500 John Drescher <drescherjm@gmail.com> wro=
te:

> On Wed, Jan 28, 2015 at 1:44 AM, lilofile <lilofile@aliyun.com> wrote:
> > kernel  linux 3.10, centos
> > when I use 5 disk to create raid5,after sync complete, I unplug a disk,=
and wait a moment, then replug the same disk.
> >
> > the original 4 disk are still a raid5 which is degraded.
> > I find the single disk  become a new raid5,but inactive,what the reason?
>=20
> stop whatever new array that shows up then use
>=20
> mdadm --manage /dev/mymddevice --re-add /dev/disk5
>=20

Also, you probably need a newer version of mdadm. Creating a new inactive
raid5 was a bug.

If you have udev configured to run "mdadm -I" on newly added devices (which=
 I
think most distros do), then adding
  POLICY action=3Dre-add

to /etc/mdadm.conf should  cause the device to automatically be added back =
to
the array when you plug it in.

NeilBrown

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