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From:   Xiao Ni <xni@redhat.com>
Date:   Tue, 12 Oct 2021 14:58:30 +0800
Message-ID: <CALTww28CsJdmVOLFeoHC8FgbHDK78h8Lncsf9fFA0RYXEj=R9A@mail.gmail.com>
Subject: Re: [PATCH RESEND] md: allow to set the fail_fast on RAID1/RAID10
To:     Li Feng <fengli@smartx.com>
Cc:     Song Liu <song@kernel.org>,
        "open list:SOFTWARE RAID (Multiple Disks) SUPPORT" 
        <linux-raid@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>
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On Mon, Oct 11, 2021 at 5:42 PM Li Feng <fengli@smartx.com> wrote:
>
> Xiao Ni <xni@redhat.com> =E4=BA=8E2021=E5=B9=B410=E6=9C=8811=E6=97=A5=E5=
=91=A8=E4=B8=80 =E4=B8=8B=E5=8D=883:49=E5=86=99=E9=81=93=EF=BC=9A
> >
> > Hi all
> >
> > Now the per device sysfs interface file state can change failfast. Do
> > we need a new file for failfast?
> >
> > I did a test. The steps are:
> >
> > mdadm -CR /dev/md0 -l1 -n2 /dev/sdb /dev/sdc --assume-clean
> > cd /sys/block/md0/md/dev-sdb
> > echo failfast > state
> > cat state
> > in_sync,failfast
>
> This works,  will it be persisted to disk?
>

mdadm --detail /dev/md0 can show the failfast information. So it
should be written in superblock.
But I don't find how md does this. I'm looking at this.

Regards
Xiao