Re: RAID 6, 6 device array - all devices lost superblock

Peter Sanders
2022-09-05T20:16:56Z

Wrote a script to do the setup:
-----
#! /usr/bin/bash

cd /mnt/backup;

DEVICES='/dev/sdb /dev/sdc /dev/sdd /dev/sde /dev/sdf /dev/sdg';
echo $DEVICES;

date;
parallel 'test -e /dev/loop{#} || mknod -m 660 /dev/loop{#} b 7 {#}'
::: $DEVICES;
ls -l /dev/loop*;

date;
parallel truncate -s300G overlay-{/} ::: $DEVICES;
ls -l /mnt/backup;

date;
parallel 'size=$(blockdev --getsize {}); loop=$(losetup -f --show --
overlay-{/}); echo 0 $size snapshot {} $loop P 8 | dmsetup create {/}'
::: $DEVICES;

date;
OVERLAYS=$(parallel echo /dev/mapper/{/} ::: $DEVICES);

dmsetup status;
-----
Ran that, then ran pvs, etc

Mon 05 Sep 2022 04:05:50 PM EDT
sdg: 0 5860533168 snapshot 16/629145600 16
sdf: 0 5860533168 snapshot 16/629145600 16
sde: 0 5860533168 snapshot 16/629145600 16
sdd: 0 5860533168 snapshot 16/629145600 16
sdc: 0 5860533168 snapshot 16/629145600 16
sdb: 0 5860533168 snapshot 16/629145600 16
root@superior:~# pvs
pvs pvscan
root@superior:~# pvs
root@superior:~# vg
vgcfgbackup vgck vgdisplay vgimport vgmknodes
vgrename vgsplit
vgcfgrestore vgconvert vgexport vgimportclone vgreduce
vgs
vgchange vgcreate vgextend vgmerge vgremove
vgscan
root@superior:~# vgs
root@superior:~# pvs -a
PV VG Fmt Attr PSize PFree
/dev/loop0 --- 0 0
/dev/loop1 --- 0 0
/dev/loop2 --- 0 0
/dev/loop3 --- 0 0
/dev/loop4 --- 0 0
/dev/loop5 --- 0 0
/dev/nvme0n1 --- 0 0
/dev/nvme0n1p1 --- 0 0
/dev/nvme0n1p5 --- 0 0
/dev/nvme0n1p6 --- 0 0
/dev/nvme0n1p7 --- 0 0
/dev/nvme0n1p8 --- 0 0
/dev/nvme0n1p9 --- 0 0
/dev/sda1 --- 0 0
root@superior:~# vgs -a
root@superior:~# vgs -a
root@superior:~# dmsetup remove
No device specified.
Command failed.
root@superior:~# echo $DEVICES

root@superior:~# dmsetup remove /dev/sdb
Device sdb not found
Command failed.
root@superior:~# cat /proc/partitions
major minor #blocks name

259 0 250059096 nvme0n1
259 1 496640 nvme0n1p1
259 2 1 nvme0n1p2
259 3 63475712 nvme0n1p5
259 4 97654784 nvme0n1p6
259 5 37888 nvme0n1p7
259 6 86913024 nvme0n1p8
259 7 1474560 nvme0n1p9
11 0 1048575 sr0
8 48 2930266584 sdd
8 16 2930266584 sdb
8 80 2930266584 sdf
8 0 1953514584 sda
8 1 1953513472 sda1
8 32 2930266584 sdc
8 64 2930266584 sde
8 96 2930266584 sdg
7 0 314572800 loop0
7 1 314572800 loop1
7 2 314572800 loop2
7 3 314572800 loop3
7 4 314572800 loop4
7 5 314572800 loop5
253 0 2930266584 dm-0
253 1 2930266584 dm-1
253 2 2930266584 dm-2
253 3 2930266584 dm-3
253 4 2930266584 dm-4
253 5 2930266584 dm-5
root@superior:~#

Should I be calling dmsetup remove for /dev/sdx or /dev/dm-n?
Since dmsetup remove fails to find /dev/sdb...

for device order -- will ls -l /dev/disk/by-id work?
These first nine lines appear to be show serial numbers.

root@superior:~# ls -l /dev/disk/by-id/
total 0
lrwxrwxrwx 1 root root 9 Sep 5 16:02 ata-MAD_DOG_LS-DVDRW_TSH652M -> ../../sr0
lrwxrwxrwx 1 root root 9 Sep 5 16:02 ata-TOSHIBA_HDWD130_477ABEJAS
-> ../../sdg
lrwxrwxrwx 1 root root 9 Sep 5 16:02 ata-TOSHIBA_HDWD130_477ALBNAS
-> ../../sdb
lrwxrwxrwx 1 root root 9 Sep 5 16:02 ata-TOSHIBA_HDWD130_Y7211KPAS
-> ../../sdc
lrwxrwxrwx 1 root root 9 Sep 5 16:02
ata-WDC_WD20EARX-00PASB0_WD-WMAZA6843376 -> ../../sda
lrwxrwxrwx 1 root root 10 Sep 5 16:02
ata-WDC_WD20EARX-00PASB0_WD-WMAZA6843376-part1 -> ../../sda1
lrwxrwxrwx 1 root root 9 Sep 5 16:02
ata-WDC_WD30EZRX-00D8PB0_WD-WCC4N0091255 -> ../../sde
lrwxrwxrwx 1 root root 9 Sep 5 16:02
ata-WDC_WD30EZRX-00DC0B0_WD-WCC1T0668790 -> ../../sdd
lrwxrwxrwx 1 root root 9 Sep 5 16:02
ata-WDC_WD30EZRX-00MMMB0_WD-WCAWZ2669166 -> ../../sdf
lrwxrwxrwx 1 root root 13 Sep 5 16:02 nvme-eui.6479a75970c003ee ->
../../nvme0n1
lrwxrwxrwx 1 root root 15 Sep 5 16:02 nvme-eui.6479a75970c003ee-part1
-> ../../nvme0n1p1
lrwxrwxrwx 1 root root 15 Sep 5 16:02 nvme-eui.6479a75970c003ee-part2
-> ../../nvme0n1p2
lrwxrwxrwx 1 root root 15 Sep 5 16:02 nvme-eui.6479a75970c003ee-part5
-> ../../nvme0n1p5
lrwxrwxrwx 1 root root 15 Sep 5 16:02 nvme-eui.6479a75970c003ee-part6
-> ../../nvme0n1p6
lrwxrwxrwx 1 root root 15 Sep 5 16:02 nvme-eui.6479a75970c003ee-part7
-> ../../nvme0n1p7
lrwxrwxrwx 1 root root 15 Sep 5 16:02 nvme-eui.6479a75970c003ee-part8
-> ../../nvme0n1p8
lrwxrwxrwx 1 root root 15 Sep 5 16:02 nvme-eui.6479a75970c003ee-part9
-> ../../nvme0n1p9
lrwxrwxrwx 1 root root 13 Sep 5 16:02 nvme-PCIe_SSD_21112925606047 ->
../../nvme0n1
lrwxrwxrwx 1 root root 15 Sep 5 16:02
nvme-PCIe_SSD_21112925606047-part1 -> ../../nvme0n1p1
lrwxrwxrwx 1 root root 15 Sep 5 16:02
nvme-PCIe_SSD_21112925606047-part2 -> ../../nvme0n1p2
lrwxrwxrwx 1 root root 15 Sep 5 16:02
nvme-PCIe_SSD_21112925606047-part5 -> ../../nvme0n1p5
lrwxrwxrwx 1 root root 15 Sep 5 16:02
nvme-PCIe_SSD_21112925606047-part6 -> ../../nvme0n1p6
lrwxrwxrwx 1 root root 15 Sep 5 16:02
nvme-PCIe_SSD_21112925606047-part7 -> ../../nvme0n1p7
lrwxrwxrwx 1 root root 15 Sep 5 16:02
nvme-PCIe_SSD_21112925606047-part8 -> ../../nvme0n1p8
lrwxrwxrwx 1 root root 15 Sep 5 16:02
nvme-PCIe_SSD_21112925606047-part9 -> ../../nvme0n1p9
lrwxrwxrwx 1 root root 9 Sep 5 16:02 wwn-0x5000039fe6d2ce25 -> ../../sdg
lrwxrwxrwx 1 root root 9 Sep 5 16:02 wwn-0x5000039fe6d2e832 -> ../../sdb
lrwxrwxrwx 1 root root 9 Sep 5 16:02 wwn-0x5000039fe6dca946 -> ../../sdc
lrwxrwxrwx 1 root root 9 Sep 5 16:02 wwn-0x50014ee15a13d994 -> ../../sdf
lrwxrwxrwx 1 root root 9 Sep 5 16:02 wwn-0x50014ee206a417d2 -> ../../sda
lrwxrwxrwx 1 root root 10 Sep 5 16:02 wwn-0x50014ee206a417d2-part1 ->
../../sda1
lrwxrwxrwx 1 root root 9 Sep 5 16:02 wwn-0x50014ee2084d406a -> ../../sdd
lrwxrwxrwx 1 root root 9 Sep 5 16:02 wwn-0x50014ee2b3d4ffa1 -> ../../sde

On Mon, Sep 5, 2022 at 3:36 PM John Stoffel <john@stoffel.org> wrote:
>
> >>>>> "Peter" == Peter Sanders <plsander@gmail.com> writes:
>
> > tried removing the setup:
> > root@superior:/mnt/backup# mdadm --stop /dev/md1
> > mdadm: stopped /dev/md1
> > root@superior:/mnt/backup# parallel 'dmsetup remove {/}; rm
> > overlay-{/}' ::: $DEVICES
> > ^C
>
> > (ran for an hour before cancel... )
>
> > root@superior:/mnt/backup# dmsetup status
> > No devices found
> > root@superior:/mnt/backupls
> > lost+found overlay-sdb overlay-sdc overlay-sdd overlay-sde
> > overlay-sdf overlay-sdg
> > root@superior:/mnt/backup# rm overlay-sd*
> > root@superior:/mnt/backup# ls /dev/loop
> > ls: cannot access '/dev/loop': No such file or directory
> > root@superior:/mnt/backup# ls /dev/loop*
> > /dev/loop0 /dev/loop2 /dev/loop4 /dev/loop6 /dev/loop-control
> > /dev/loop1 /dev/loop3 /dev/loop5 /dev/loop7
> > root@superior:/mnt/backup# parallel losetup -d ::: /dev/loop[0-9]*
> > losetup: /dev/loop6: detach failed: No such device or address
> > losetup: /dev/loop7: detach failed: No such device or address
> > root@superior:/mnt/backup# ls /dev/loop*
> > /dev/loop0 /dev/loop2 /dev/loop4 /dev/loop6 /dev/loop-control
> > /dev/loop1 /dev/loop3 /dev/loop5 /dev/loop7
> > root@superior:/mnt/backup# ls -la /dev/lo*
> > lrwxrwxrwx 1 root root 28 Sep 2 20:22 /dev/log ->
> > /run/systemd/journal/dev-log
> > brw-rw---- 1 root disk 7, 0 Sep 2 20:32 /dev/loop0
> > brw-rw---- 1 root disk 7, 1 Sep 2 20:32 /dev/loop1
> > brw-rw---- 1 root disk 7, 2 Sep 2 20:32 /dev/loop2
> > brw-rw---- 1 root disk 7, 3 Sep 2 20:32 /dev/loop3
> > brw-rw---- 1 root disk 7, 4 Sep 2 20:32 /dev/loop4
> > brw-rw---- 1 root disk 7, 5 Sep 2 20:32 /dev/loop5
> > brw-rw---- 1 root disk 7, 6 Sep 2 20:32 /dev/loop6
> > brw-rw---- 1 root disk 7, 7 Sep 2 20:32 /dev/loop7
> > crw-rw---- 1 root disk 10, 237 Sep 2 20:32 /dev/loop-control
> > root@superior:/mnt/backup# losetup -d ::: /dev/loop70
> > losetup: :::: failed to use device: No such device
> > root@superior:/mnt/backup# losetup -d ::: /dev/loop7
> > losetup: :::: failed to use device: No such device
> > root@superior:/mnt/backup# losetup -d /dev/loop7
> > losetup: /dev/loop7: detach failed: No such device or address
> > root@superior:/mnt/backup# ls -la /dev/loop*
> > brw-rw---- 1 root disk 7, 0 Sep 2 20:32 /dev/loop0
> > brw-rw---- 1 root disk 7, 1 Sep 2 20:32 /dev/loop1
> > brw-rw---- 1 root disk 7, 2 Sep 2 20:32 /dev/loop2
> > brw-rw---- 1 root disk 7, 3 Sep 2 20:32 /dev/loop3
> > brw-rw---- 1 root disk 7, 4 Sep 2 20:32 /dev/loop4
> > brw-rw---- 1 root disk 7, 5 Sep 2 20:32 /dev/loop5
> > brw-rw---- 1 root disk 7, 6 Sep 2 20:32 /dev/loop6
> > brw-rw---- 1 root disk 7, 7 Sep 2 20:32 /dev/loop7
> > crw-rw---- 1 root disk 10, 237 Sep 2 20:32 /dev/loop-control
> > root@superior:/mnt/backup# losetup /dev/loop7
> > losetup: /dev/loop7: No such file or directory
> > root@superior:/mnt/backup# losetup /dev/loop5
> > losetup: /dev/loop5: No such file or directory
> > root@superior:/mnt/backup#
>
>
> > not sure why losetup cannot see the existing /dev/loopx devices.
>
> I was reading the dmsetup man page and it said that if the devices are
> open, when you do a remove, it sorta fails them and then blocks them
> as unable to have more IO sent to them. But honestly I'm not an
> expert on dmsetup.
>
> But sure, try to reboot each time, but you also need to make sure the
> disks are in the same positions each time after reboot, so look at the
> serial numbers.
>
> lsscsi -g -l
>
> might be enough to give you unique or instead use:
>
> hdparm -i /dev/sda | grep SerialNo
>
> to get the info and keep track of which disk is in which order.
>
> John
>
>
>
> > On Fri, Sep 2, 2022 at 8:39 PM Peter Sanders <plsander@gmail.com> wrote:
> >>
> >> Repeat of run 1
> >>
> >> plsander@superior:~$ su -
> >> Password:
> >> root@superior:~# cat /proc/partitions
> >> major minor #blocks name
> >>
> >> 259 0 250059096 nvme0n1
> >> 259 1 496640 nvme0n1p1
> >> 259 2 1 nvme0n1p2
> >> 259 3 63475712 nvme0n1p5
> >> 259 4 97654784 nvme0n1p6
> >> 259 5 37888 nvme0n1p7
> >> 259 6 86913024 nvme0n1p8
> >> 259 7 1474560 nvme0n1p9
> >> 8 16 2930266584 sdb
> >> 8 80 2930266584 sdf
> >> 8 0 1953514584 sda
> >> 8 1 1953513472 sda1
> >> 8 32 2930266584 sdc
> >> 8 96 2930266584 sdg
> >> 8 64 2930266584 sde
> >> 8 48 2930266584 sdd
> >> 11 0 1048575 sr0
> >> root@superior:~# cat /proc/mdstat
> >> Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5]
> >> [raid4] [raid10]
> >> unused devices: <none>
> >> root@superior:~# DEVICES="/dev/sdb /dev/sdc /dev/sdd /dev/sde /dev/sdf /dev/sdg"
> >> root@superior:~# echo $DEVICES
> >> /dev/sdb /dev/sdc /dev/sdd /dev/sde /dev/sdf /dev/sdg
> >> root@superior:~# parallel 'test -e /dev/loop{#} || mknod -m 660
> >> /dev/loop{#} b 7 {#}' ::: $DEVICES
> >> root@superior:~# ls /dev/lo
> >> log loop2 loop4 loop6
> >> loop1 loop3 loop5 loop-control
> >> root@superior:~# ls /dev/lo*
> >> /dev/log /dev/loop1 /dev/loop2 /dev/loop3 /dev/loop4 /dev/loop5
> >> /dev/loop6 /dev/loop-control
> >> root@superior:~# ls -l /dev/loop*
> >> brw-rw---- 1 root root 7, 1 Sep 2 20:30 /dev/loop1
> >> brw-rw---- 1 root root 7, 2 Sep 2 20:30 /dev/loop2
> >> brw-rw---- 1 root root 7, 3 Sep 2 20:30 /dev/loop3
> >> brw-rw---- 1 root root 7, 4 Sep 2 20:30 /dev/loop4
> >> brw-rw---- 1 root root 7, 5 Sep 2 20:30 /dev/loop5
> >> brw-rw---- 1 root root 7, 6 Sep 2 20:30 /dev/loop6
> >> crw-rw---- 1 root disk 10, 237 Sep 2 20:22 /dev/loop-control
> >> root@superior:~# cd /mnt/backup/
> >> root@superior:/mnt/backup# parallel truncate -s4000G overlay-{/} ::: $DEVICES
> >> root@superior:/mnt/backup# ls -l
> >> total 16
> >> drwx------ 2 root root 16384 Aug 28 18:50 lost+found
> >> -rw-r--r-- 1 root root 4294967296000 Sep 2 20:31 overlay-sdb
> >> -rw-r--r-- 1 root root 4294967296000 Sep 2 20:31 overlay-sdc
> >> -rw-r--r-- 1 root root 4294967296000 Sep 2 20:31 overlay-sdd
> >> -rw-r--r-- 1 root root 4294967296000 Sep 2 20:31 overlay-sde
> >> -rw-r--r-- 1 root root 4294967296000 Sep 2 20:31 overlay-sdf
> >> -rw-r--r-- 1 root root 4294967296000 Sep 2 20:31 overlay-sdg
> >> root@superior:/mnt/backup# rm over*
> >> root@superior:/mnt/backup# parallel truncate -s300G overlay-{/} ::: $DEVICES
> >> root@superior:/mnt/backup# ls -la
> >> total 24
> >> drwxr-xr-x 3 root root 4096 Sep 2 20:31 .
> >> drwxr-xr-x 7 root root 4096 Aug 29 09:17 ..
> >> drwx------ 2 root root 16384 Aug 28 18:50 lost+found
> >> -rw-r--r-- 1 root root 322122547200 Sep 2 20:31 overlay-sdb
> >> -rw-r--r-- 1 root root 322122547200 Sep 2 20:31 overlay-sdc
> >> -rw-r--r-- 1 root root 322122547200 Sep 2 20:31 overlay-sdd
> >> -rw-r--r-- 1 root root 322122547200 Sep 2 20:31 overlay-sde
> >> -rw-r--r-- 1 root root 322122547200 Sep 2 20:31 overlay-sdf
> >> -rw-r--r-- 1 root root 322122547200 Sep 2 20:31 overlay-sdg
> >> root@superior:/mnt/backup# dmsetup status
> >> No devices found
> >> root@superior:/mnt/backup# date
> >> Fri 02 Sep 2022 08:32:11 PM EDT
> >> root@superior:/mnt/backup# parallel 'size=$(blockdev --getsize {});
> >> loop=$(losetup -f --show -- overlay-{/}); echo 0 $size snapshot {}
> >> $loop P 8 | dmsetup create {/}' ::: $DEVICES
> >> root@superior:/mnt/backup# date
> >> Fri 02 Sep 2022 08:32:20 PM EDT
> >> root@superior:/mnt/backup# dmsetup status
> >> sdg: 0 5860533168 snapshot 16/629145600 16
> >> sdf: 0 5860533168 snapshot 16/629145600 16
> >> sde: 0 5860533168 snapshot 16/629145600 16
> >> sdd: 0 5860533168 snapshot 16/629145600 16
> >> sdc: 0 5860533168 snapshot 16/629145600 16
> >> sdb: 0 5860533168 snapshot 16/629145600 16
> >> root@superior:/mnt/backup# OVERLAYS=$(parallel echo /dev/mapper/{/}
> >> ::: $DEVICES)
> >> root@superior:/mnt/backup# echo $OVERLAYS
> >> /dev/mapper/sdb /dev/mapper/sdc /dev/mapper/sdd /dev/mapper/sde
> >> /dev/mapper/sdf /dev/mapper/sdg
> >> root@superior:/mnt/backup# mdadm --create /dev/md1 --level=raid6 -n 6
> >> --assume-clean $OVERLAYS
> >> mdadm: partition table exists on /dev/mapper/sdb
> >> mdadm: partition table exists on /dev/mapper/sdc
> >> mdadm: partition table exists on /dev/mapper/sdc but will be lost or
> >> meaningless after creating array
> >> mdadm: partition table exists on /dev/mapper/sdd
> >> mdadm: partition table exists on /dev/mapper/sdd but will be lost or
> >> meaningless after creating array
> >> mdadm: partition table exists on /dev/mapper/sde
> >> mdadm: partition table exists on /dev/mapper/sde but will be lost or
> >> meaningless after creating array
> >> mdadm: partition table exists on /dev/mapper/sdf
> >> mdadm: partition table exists on /dev/mapper/sdf but will be lost or
> >> meaningless after creating array
> >> mdadm: partition table exists on /dev/mapper/sdg
> >> mdadm: partition table exists on /dev/mapper/sdg but will be lost or
> >> meaningless after creating array
> >> Continue creating array? y
> >> mdadm: Defaulting to version 1.2 metadata
> >> mdadm: array /dev/md1 started.
> >> root@superior:/mnt/backup# ls -l /dev/md*
> >> brw-rw---- 1 root disk 9, 1 Sep 2 20:34 /dev/md1
> >> root@superior:/mnt/backup# fsck /dev/md1
> >> fsck from util-linux 2.36.1
> >> e2fsck 1.46.2 (28-Feb-2021)
> >> ext2fs_open2: Bad magic number in super-block
> >> fsck.ext2: Superblock invalid, trying backup blocks...
> >> fsck.ext2: Bad magic number in super-block while trying to open /dev/md1
> >>
> >> The superblock could not be read or does not describe a valid ext2/ext3/ext4
> >> filesystem. If the device is valid and it really contains an ext2/ext3/ext4
> >> filesystem (and not swap or ufs or something else), then the superblock
> >> is corrupt, and you might try running e2fsck with an alternate superblock:
> >> e2fsck -b 8193 <device>
> >> or
> >> e2fsck -b 32768 <device>
> >>
> >> root@superior:/mnt/backup# blkid /dev/md1
> >> root@superior:/mnt/backup#
> >> root@superior:/mnt/backup# cat /proc/mdstat
> >> Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5]
> >> [raid4] [raid10]
> >> md1 : active raid6 dm-3[5] dm-2[4] dm-1[3] dm-5[2] dm-0[1] dm-4[0]
> >> 11720536064 blocks super 1.2 level 6, 512k chunk, algorithm 2
> >> [6/6] [UUUUUU]
> >> bitmap: 0/22 pages [0KB], 65536KB chunk
> >>
> >> unused devices: <none>
> >> root@superior:/mnt/backup#
> >>
> >> Some questions -
> >> - is the easiest 'reset for next run' to reboot and rebuild?
> >>
> >>
> >> On Fri, Sep 2, 2022 at 3:12 PM John Stoffel <john@stoffel.org> wrote:
> >> >
> >> > >>>>> "Peter" == Peter Sanders <plsander@gmail.com> writes:
> >> >
> >> > Peter, please include the output of all the commands, not just the
> >> > commands themselves. See my comments below.
> >> >
> >> >
> >> > > Question on restarting from scratch...
> >> > > How to reset to the starting point?
> >> >
> >> > I think you need to blow away the loop devices and re-create them.
> >> >
> >> > Or at least blow away the dmsetup devices you just created.
> >> >
> >> > It might be quickest to just reboot. What OS are you using for the
> >> > recovery? Is it a recent live image? Sorry for asking so many
> >> > questions... some of this is new to me too.
> >> >
> >> >
> >> > > dmsetup, both for remove and create of the overlay seems to be hanging.
> >> >
> >> > > On Fri, Sep 2, 2022 at 10:56 AM Peter Sanders <plsander@gmail.com> wrote:
> >> > >>
> >> > >> contents of /proc/mdstat
> >> > >>
> >> > >> root@superior:/mnt/backup# cat /proc/mdstat
> >> > >> Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5]
> >> > >> [raid4] [raid10]
> >> > >> unused devices: <none>
> >> > >> root@superior:/mnt/backup#
> >> > >>
> >> > >>
> >> > >>
> >> > >> Here are the steps I ran (minus some mounting other devices and
> >> > >> looking around for mdadm tracks on the old os disk)
> >> > >>
> >> > >> 410 DEVICES=$(cat /proc/partitions | parallel --tagstring {5}
> >> > >> --colsep ' +' mdadm -E /dev/{5} |grep $UUID | parallel --colsep '\t'
> >> > >> echo /dev/{1})
> >> > >> 411 apt install parallel
> >> > >> 412 DEVICES=$(cat /proc/partitions | parallel --tagstring {5}
> >> > >> --colsep ' +' mdadm -E /dev/{5} |grep $UUID | parallel --colsep '\t'
> >> > >> echo /dev/{1})
> >> > >> 413 echo $DEVICES
> >> >
> >> > So you found no MD RAID super blocks on any of the base devices. You
> >> > can skip this step moving forward.
> >> >
> >> > >> 414 cat /proc/partitions
> >> > >> 415 DEVICES=/dev/sdb /dev/sdc /dev/sdd /dev/sde /dev/sdf /dev/sdg
> >> > >> 416 DEVICES="/dev/sdb /dev/sdc /dev/sdd /dev/sde /dev/sdf /dev/sdg"
> >> > >> 417 echo $DEVICES
> >> > >> 418 parallel 'test -e /dev/loop{#} || mknod -m 660 /dev/loop{#} b 7
> >> > >> {#}' ::: $DEVICES
> >> > >> 419 ls /dev/loop*
> >> >
> >> > Can you show the output of all these commands, not just the commands please?
> >> >
> >> > >> 423 parallel truncate -s300G overlay-{/} ::: $DEVICES
> >> >
> >> > >> 427 parallel 'size=$(blockdev --getsize {}); loop=$(losetup -f
> >> > >> --show -- overlay-{/}); echo 0 $size snapshot {} $loop P 8 | dmsetup
> >> > >> create {/}' ::: $DEVICES
> >> > >> 428 ls /dev/mapper/
> >> >
> >> > This is some key output to view.
> >> >
> >> > >> 429 OVERLAYS=$(parallel echo /dev/mapper/{/} ::: $DEVICES)
> >> > >> 430 echo $OVERLAYS
> >> >
> >> > What are the overlays?
> >> >
> >> > >> 431 dmsetup status
> >> >
> >> > What did this command show?
> >> >
> >> > >> 432 mdadm --assemble --force /dev/md1 $OVERLAYS
> >> >
> >> > And here is where I think you need to put --assume-clean when using
> >> > 'create' command instead. It's not going to assemble anything because
> >> > the info was wiped. I *think* you really want:
> >> >
> >> > mdadm --create /dev/md1 --level=raid6 -n 6 --assume-clean $OVERLAYS
> >> >
> >> > And once you do this above command and it comes back, do:
> >> >
> >> > cat /proc/mdstat
> >> >
> >> > and show all the output please!
> >> >
> >> > >> 433 history
> >> > >> 434 dmsetup status
> >> > >> 435 echo $OVERLAYS
> >> > >> 436 mdadm --assemble --force /dev/md0 $OVERLAYS
> >> > >> 437 cat /proc/partitions
> >> > >> 438 mkdir /mnt/oldroot
> >> > >> << look for inird mdadm files >>
> >> > >> 484 echo $OVERLAYS
> >> > >> 485 mdadm --create /dev/md0 --level=raid6 -n 6 /dev/mapper/sdb
> >> > >> /dev/mapper/sdc /dev/mapper/sdd /dev/mapper/sde /dev/mapper/sdf
> >> > >> /dev/mapper/sdg
> >> >
> >> > I'm confused here, what is the difference between the md1 you
> >> > assembled above, and the md0 you're doing here?
> >> >
> >> > >> << cancelled out of 485, review instructions... >>
> >> > >> 486 mdadm --create /dev/md0 --level=raid6 -n 6 /dev/mapper/sdb
> >> > >> /dev/mapper/sdc /dev/mapper/sdd /dev/mapper/sde /dev/mapper/sdf
> >> > >> /dev/mapper/sdg
> >> > >> 487 fsck -n /dev/md0
> >> >
> >> > And what output did you get here? Did it find a filesystem? You might want
> >> > to try:
> >> >
> >> > blkid /dev/md0
> >> >
> >> >
> >> > >> 488 mdadm --stop /dev/md0
> >> > >> 489 echo $DEVICES
> >> > >> 490 parallel 'dmsetup remove {/}; rm overlay-{/}' ::: $DEVICES
> >> > >> 491 dmsetup status
> >> >
> >> > This all worked properly? No errors?
> >> >
> >> > I gave up after this because it's not clear what the results really
> >> > are. If you don't find a filesystem that fsck's cleanly, then you
> >> > should just need to stop the array, then re-create it but shuffle the
> >> > order of the devices.
> >> >
> >> > Instead of disk in order of "sdb sdc sdd... sdN", you would try the
> >> > order "sdc sdd ... sdN sdb". See how I moved sdb to the end of the
> >> > list of devices? With six disks, you have I think 6 factorial options
> >> > to try. Which is alot of options to go though, and why you need to
> >> > automate this more. But also keep a log and show the output!
> >> >
> >> > John
> >> >
> >> >
> >> > >> 492 ls
> >> > >> 493 rm overlay-*
> >> > >> 494 ls
> >> > >> 495 parallel losetup -d ::: /dev/loop[0-9]*
> >> > >> 496 parallel 'test -e /dev/loop{#} || mknod -m 660 /dev/loop{#} b 7
> >> > >> {#}' ::: $DEVICES
> >> > >> 497 parallel truncate -s300G overlay-{/} ::: $DEVICES
> >> > >> 498 parallel 'size=$(blockdev --getsize {}); loop=$(losetup -f
> >> > >> --show -- overlay-{/}); echo 0 $size snapshot {} $loop P 8 | dmsetup
> >> > >> create {/}' ::: $DEVICES
> >> > >> 499 dmsetup status
> >> > >> 500 /sbin/reboot
> >> > >> 501 history
> >> > >> 502 dmsetup status
> >> > >> 503 mount
> >> > >> 504 cat /proc/partitions
> >> > >> 505 nano /etc/fstab
> >> > >> 506 mount /mnt/backup/
> >> > >> 507 ls /mnt/backup/
> >> > >> 508 rm /mnt/backup/
> >> > >> 509 rm /mnt/backup/overlay-sd*
> >> > >> 510 emacs setupOverlay &
> >> > >> 511 ps auxww | grep emacs
> >> > >> 512 kill 65017
> >> > >> 513 ls /dev/loo*
> >> > >> 514 DEVICES='/dev/sdb /dev/sdc /dev/sdd /dev/sde /dev/sdf /dev/sdg'
> >> > >> 515 echo $DEVICES
> >> > >> 516 parallel 'test -e /dev/loop{#} || mknod -m 660 /dev/loop{#} b
> >> > >> 7 {#}' ::: $DEVICES
> >> > >> 517 ls /dev/loo*
> >> > >> 518 parallel truncate -s4000G overlay-{/} ::: $DEVICES
> >> > >> 519 ls
> >> > >> 520 rm overlay-sd*
> >> > >> 521 cd /mnt/bak
> >> > >> 522 cd /mnt/backup/
> >> > >> 523 ls
> >> > >> 524 parallel truncate -s4000G overlay-{/} ::: $DEVICES
> >> > >> 525 ls -la
> >> > >> 526 blockdev --getsize /dev/sdb
> >> > >> 527 man losetup
> >> > >> 528 man losetup
> >> > >> 529 parallel 'size=$(blockdev --getsize {}); loop=$(losetup -f
> >> > >> --show -- overlay-{/}); echo 0 $size snapshot {} $loop P 8 | dmsetup
> >> > >> create {/}' ::: $DEVICES
> >> > >> 530 dmsetup status
> >> > >> 531 history | grep mdadm
> >> > >> 532 history
> >> > >> 533 dmsetup status
> >> > >> 534 history | grep dmsetup
> >> > >> 535 dmsetup status
> >> > >> 536 dmsetup remove sdg
> >> > >> 537 dmsetup ls --tree
> >> > >> 538 lsof
> >> > >> 539 dmsetup ls --tre
> >> > >> 540 dmsetup ls --tree
> >> > >> 541 lsof | grep -i sdg
> >> > >> 542 lsof | grep -i sdf
> >> > >> 543 history |grep dmsetup | less
> >> > >> 544 dmsetup status
> >> > >> 545 history > ~plsander/Documents/raidIssues/joblog
> >> > >>
> >> > >> On Wed, Aug 31, 2022 at 4:37 PM John Stoffel <john@stoffel.org> wrote:
> >> > >> >
> >> > >> > >>>>> "Peter" == Peter Sanders <plsander@gmail.com> writes:
> >> > >> >
> >> > >> > > encountering a puzzling situation.
> >> > >> > > dmsetup is failing to return.
> >> > >> >
> >> > >> > I don't think you need to use dmsetup in your case, but can you post
> >> > >> > *all* the commands you ran before you got to this point, and the
> >> > >> > output of
> >> > >> >
> >> > >> > cat /proc/mdstat
> >> > >> >
> >> > >> > as well? Thinking on this some more, you might need to actually also
> >> > >> > add:
> >> > >> >
> >> > >> > --assume-clean
> >> > >> >
> >> > >> > to the 'mdadm create ....' string, since you don't want it to zero the
> >> > >> > array or anything.
> >> > >> >
> >> > >> > Sorry for not remembering this at the time!
> >> > >> >
> >> > >> > So if you can, please just start over from scratch, showing the setup
> >> > >> > of the loop devices, the overlayfs setup, and the building the RAID6
> >> > >> > array, along with the cat /proc/mdstat after you do the initial build.
> >> > >> >
> >> > >> > John
> >> > >> >
> >> > >> > P.S. For those who hated my email citing tool, I pulled it out for
> >> > >> > now. Only citing with > now. :-)
> >> > >> >
> >> > >> > > root@superior:/mnt/backup# dmsetup status
> >> > >> > > sdg: 0 5860533168 snapshot 16/8388608000 16
> >> > >> > > sdf: 0 5860533168 snapshot 16/8388608000 16
> >> > >> > > sde: 0 5860533168 snapshot 16/8388608000 16
> >> > >> > > sdd: 0 5860533168 snapshot 16/8388608000 16
> >> > >> > > sdc: 0 5860533168 snapshot 16/8388608000 16
> >> > >> > > sdb: 0 5860533168 snapshot 16/8388608000 16
> >> > >> >
> >> > >> > > dmsetup remove sdg runs for hours.
> >> > >> > > Canceled it, ran dmsetup ls --tree and find that sdg is not present in the list.
> >> > >> >
> >> > >> > > dmsetup status shows:
> >> > >> > > sdf: 0 5860533168 snapshot 16/8388608000 16
> >> > >> > > sde: 0 5860533168 snapshot 16/8388608000 16
> >> > >> > > sdd: 0 5860533168 snapshot 16/8388608000 16
> >> > >> > > sdc: 0 5860533168 snapshot 16/8388608000 16
> >> > >> > > sdb: 0 5860533168 snapshot 16/8388608000 16
> >> > >> >
> >> > >> > > dmsetup ls --tree
> >> > >> > > root@superior:/mnt/backup# dmsetup ls --tree
> >> > >> > > sdf (253:3)
> >> > >> > > ├─ (7:3)
> >> > >> > > └─ (8:80)
> >> > >> > > sde (253:1)
> >> > >> > > ├─ (7:1)
> >> > >> > > └─ (8:64)
> >> > >> > > sdd (253:2)
> >> > >> > > ├─ (7:2)
> >> > >> > > └─ (8:48)
> >> > >> > > sdc (253:0)
> >> > >> > > ├─ (7:0)
> >> > >> > > └─ (8:32)
> >> > >> > > sdb (253:5)
> >> > >> > > ├─ (7:5)
> >> > >> > > └─ (8:16)
> >> > >> >
> >> > >> > > any suggestions?
> >> > >> >
> >> > >> >
> >> > >> >
> >> > >> > > On Tue, Aug 30, 2022 at 2:03 PM Wols Lists <antlists@youngman.org.uk> wrote:
> >> > >> > >>
> >> > >> > >> On 30/08/2022 14:27, Peter Sanders wrote:
> >> > >> > >> >
> >> > >> > >> > And the victory conditions would be a mountable file system that passes a fsck?
> >> > >> > >>
> >> > >> > >> Yes. Just make sure you delve through the file system a bit and satisfy
> >> > >> > >> yourself it looks good, too ...
> >> > >> > >>
> >> > >> > >> Cheers,
> >> > >> > >> Wol