Re: Raid-6 won't boot

From: Roger Heflin <rogerheflin@gmail.com>
To: Alexander Shenkin <al@shenkin.org>
Cc: antlists <antlists@youngman.org.uk>,
	Linux-RAID <linux-raid@vger.kernel.org>
Subject: Re: Raid-6 won't boot
Date: Mon, 30 Mar 2020 12:21:24 -0500	[thread overview]
Message-ID: <CAAMCDefXygV4CZdxadfRFAV+HeEqnY8nWG1hpsVi4tBf1PYYww@mail.gmail.com> (raw)
In-Reply-To: <fa7e9b6d-28f3-8c9f-0901-eeac761e382f@shenkin.org>

do this against each partition that had it:

 mdadm --examine /dev/sd***

It seems like it is not seeing it as a md-raid.

On Mon, Mar 30, 2020 at 11:13 AM Alexander Shenkin <al@shenkin.org> wrote:
>
> Thanks Roger,
>
> The only line that isn't commented out in /etc/mdadm.conf is "DEVICE
> partitions"...
>
> Thanks,
>
> Allie
>
> On 3/30/2020 4:53 PM, Roger Heflin wrote:
> > That seems really odd.  Is the raid456 module loaded?
> >
> > On mine I see messages like this for each disk it scanned and
> > considered as maybe possibly being an array member.
> >  kernel: [   83.468700] md/raid:md13: device sdi3 operational as raid disk 5
> > and messages like this:
> >  md/raid:md14: not clean -- starting background reconstruction
> >
> > You might look at /etc/mdadm.conf on the rescue cd and see if it has a
> > DEVICE line that limits what is being scanned.
> >
> > On Mon, Mar 30, 2020 at 10:13 AM Alexander Shenkin <al@shenkin.org> wrote:
> >> Thanks Roger,
> >>
> >> that grep just returns the detection of the raid1 (md127).  See dmesg
> >> and mdadm --detail results attached.
> >>
> >> Many thanks,
> >> allie
> >>
> >> On 3/28/2020 1:36 PM, Roger Heflin wrote:
> >>> Try this grep:
> >>> dmesg | grep "md/raid", if that returns nothing if you can just send
> >>> the entire dmesg.
> >>>
> >>> On Sat, Mar 28, 2020 at 2:47 AM Alexander Shenkin <al@shenkin.org> wrote:
> >>>> Thanks Roger.  dmesg has nothing in it referring to md126 or md127....
> >>>> any other thoughts on how to investigate?
> >>>>
> >>>> thanks,
> >>>> allie
> >>>>
> >>>> On 3/27/2020 3:55 PM, Roger Heflin wrote:
> >>>>> A non-assembled array always reports raid1.
> >>>>>
> >>>>> I would run "dmesg | grep md126" to start with and see what it reports it saw.
> >>>>>
> >>>>> On Fri, Mar 27, 2020 at 10:29 AM Alexander Shenkin <al@shenkin.org> wrote:
> >>>>>> Thanks Wol,
> >>>>>>
> >>>>>> Booting in SystemRescueCD and looking in /proc/mdstat, two arrays are
> >>>>>> reported.  The first (md126) in reported as inactive with all 7 disks
> >>>>>> listed as spares.  The second (md127) is reported as active
> >>>>>> auto-read-only with all 7 disks operational.  Also, the only
> >>>>>> "personality" reported is Raid1.  I could go ahead with your suggestion
> >>>>>> of mdadm --stop array and then mdadm --assemble, but I thought the
> >>>>>> reporting of just the Raid1 personality was a bit strange, so wanted to
> >>>>>> check in before doing that...
> >>>>>>
> >>>>>> Thanks,
> >>>>>> Allie
> >>>>>>
> >>>>>> On 3/26/2020 10:00 PM, antlists wrote:
> >>>>>>> On 26/03/2020 17:07, Alexander Shenkin wrote:
> >>>>>>>> I surely need to boot with a rescue disk of some sort, but from there,
> >>>>>>>> I'm not sure exactly when I should do.  Any suggestions are very welcome!
> >>>>>>> Okay. Find a liveCD that supports raid (hopefully something like
> >>>>>>> SystemRescueCD). Make sure it has a very recent kernel and the latest
> >>>>>>> mdadm.
> >>>>>>>
> >>>>>>> All being well, the resync will restart, and when it's finished your
> >>>>>>> system will be fine. If it doesn't restart on its own, do an "mdadm
> >>>>>>> --stop array", followed by an "mdadm --assemble"
> >>>>>>>
> >>>>>>> If that doesn't work, then
> >>>>>>>
> >>>>>>> https://raid.wiki.kernel.org/index.php/Linux_Raid#When_Things_Go_Wrogn
> >>>>>>>
> >>>>>>> Cheers,
> >>>>>>> Wol