Mirror RAID clean, degraded

tazzz013 · Sep 19th 2021

Hello,

I have an issue with my Mirror RAID in my OMV. I lost power about a week ago, and logged in to OMV and noticed Raid said clean/degraded. I check and both drives are showing "green" under smart. I am using 2- HITACHI 0F14683 Ultrastar A7K4000 4TB 7200 RPM 64MB cache SATA 6.0Gb/s 3.5 internal hard drives. I have read some other post, but just confused me more. I do have replacement drives on hand if needed. Hopefully not.

Any help from people more knowledgeable would be great. Not how to insert commands I ran, so they are attached.

Thanks!

raid1.txt raid.txt

geaves · Sep 19th 2021

ssh into omv and post the output of the first five commands using </> on the menu

tazzz013 · Sep 19th 2021

Thanks for the reply and the explanation on how to insert the code.

Code

root@openmediavault:~# cat /proc/mdstat
Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10]
md0 : active raid1 sda[0]
      3906887488 blocks super 1.2 [2/1] [U_]
      bitmap: 26/30 pages [104KB], 65536KB chunk

unused devices: <none>

Code

root@openmediavault:~# blkid
/dev/sdb1: UUID="67f8957f-4256-43ef-a546-498710a572b3" TYPE="ext4" PARTUUID="951c56cc-01"
/dev/sdb5: UUID="e9fbcafa-57d3-4b1f-84fd-3817730f2d34" TYPE="swap" PARTUUID="951c56cc-05"
/dev/sda: UUID="1ac92da3-fccb-cadf-9c4a-9dc00083c1ca" UUID_SUB="1ba3b553-71cb-9121-72d4-7f7d9d4095d9" LABEL="openmediavault:0" TYPE="linux_raid_member"
/dev/md0: LABEL="RAID" UUID="012310dd-0a1d-4e68-bf83-079109e5f9ec" TYPE="ext4"
/dev/sdd: UUID="1ac92da3-fccb-cadf-9c4a-9dc00083c1ca" UUID_SUB="5c462bbe-2613-4aa3-9102-cb1917d7df2d" LABEL="openmediavault:0" TYPE="linux_raid_member"
/dev/sdc1: UUID="8A58FCA958FC9563" TYPE="ntfs" PARTUUID="95cc0009-01"

Code

root@openmediavault:~# fdisk -l | grep "Disk "
Disk /dev/sdb: 74.5 GiB, 80000000000 bytes, 156250000 sectors
Disk model: ST3808110AS
Disk identifier: 0x951c56cc
Disk /dev/sda: 3.7 TiB, 4000787030016 bytes, 7814037168 sectors
Disk model: HITACHI HUS72404
Disk /dev/sdd: 3.7 TiB, 4000787030016 bytes, 7814037168 sectors
Disk model: HITACHI HUS72404
Disk /dev/md0: 3.7 TiB, 4000652787712 bytes, 7813774976 sectors
Disk /dev/sdc: 465.8 GiB, 500107862016 bytes, 976773168 sectors
Disk model: 418AS  External
Disk identifier: 0x95cc0009

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Code

root@openmediavault:~# cat /etc/mdadm/mdadm.conf
# mdadm.conf
#
# Please refer to mdadm.conf(5) for information about this file.
#

# by default, scan all partitions (/proc/partitions) for MD superblocks.
# alternatively, specify devices to scan, using wildcards if desired.
# Note, if no DEVICE line is present, then "DEVICE partitions" is assumed.
# To avoid the auto-assembly of RAID devices a pattern that CAN'T match is
# used if no RAID devices are configured.
DEVICE partitions

# auto-create devices with Debian standard permissions
CREATE owner=root group=disk mode=0660 auto=yes

# automatically tag new arrays as belonging to the local system
HOMEHOST <system>

# definitions of existing MD arrays
ARRAY /dev/md0 metadata=1.2 name=openmediavault:0 UUID=1ac92da3:fccbcadf:9c4a9dc0:0083c1ca
MAILADDR root

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Code

root@openmediavault:~# mdadm --detail --scan --verbose
ARRAY /dev/md0 level=raid1 num-devices=2 metadata=1.2 name=openmediavault:0 UUID=1ac92da3:fccbcadf:9c4a9dc0:0083c1ca
   devices=/dev/sda

geaves · Sep 19th 2021

mdadm --add /dev/md0 /dev/sdd should add the missing drive back

tazzz013 · Sep 19th 2021

Thanks geaves!

Is there anything I need to do before or after running that command?

Also, what is it in the logs that showed you that? I looked at them, but I am still new to this part of OVM.

Thanks again for the quick reply.

geaves · Sep 19th 2021

Quote from tazzz013

Is there anything I need to do before or after running that command

There shouldn't be

Quote from tazzz013

Also, what is it in the logs that showed you that

The output you posted in post 3, showed the state of the raid, the devices in the raid and the information contained in the conf file.

A better way of doing this is run the drives as individuals, one for data and one for backup, so you rsync the data drive to the second drive.

The purpose of raid is about availability, when your raid went into a degraded state you still had access to your data, but if both drives died simultaneously then you have nothing. That's why even with a raid setup a backup procedure is a must.

tazzz013 · Sep 19th 2021

That command did the job! My raid is back to normal. I looked again at the logs I posted, still can't figure out what it is you saw.

As far as backing up, if I were to add another drive, not part of the raid obviously, I should be able to use rsync to back it up correct?

Thank you again for all your help!

geaves · Sep 19th 2021

Quote from tazzz013

As far as backing up, if I were to add another drive, not part of the raid obviously, I should be able to use rsync to back it up correct

Yes, it's what I do, I backup all my shares to a single drive in my server

tazzz013 · Sep 19th 2021

Makes perfect sense. Just added another disk, will figure out how to setup rsync next.

Can you please tell me what it is you saw in the logs that resulted in your fix?

geaves · Sep 20th 2021

The first one cat /proc/mdstat gives the raid reference, whether the raid is active, active (auto-read-only) or inactive, the raid type i.e. raid1, raid5, raid6 etc and the drives active within the raid.

So from your output;

raid reference = md0

state of raid = active

raid type = raid1

drives = /dev/sda

The above told me a drive was missing

blkid from the man pages -> command line utility to locate/print block device attributes

This is important as it will give information on TYPE, this will tell you the file system type

So from your output;

/dev/sdd was the missing drive from your array

cat /etc/mdadm/mdadm.conf

This gives the configuration on the array stored in the mdadm conf file

fdisk

Lists information about the drives

mdadm --examine

This will confirm the output from mdstat, most of the time I don't use this as mdadm --detail will give more information

Rather than use the command line it may have worked using the GUI by selecting recover on the menu under raid management. This sometimes works but most of the time it doesn't.

If the output from mdstat had shown the array as inactive the array would not be listed in blkid and would have meant running --assemble to re assemble the array

tazzz013 · Sep 20th 2021

Excellent explanation! Now I understand it perfect. Hopefully won't happen again, but now I know how to fix it.

Thanks you again geaves for all you help!

chuvihi · Sep 30th 2021

Hi geaves, I have the same issue as tazzz013 but now I cannot recover the RADI using the command "mdadm --add /dev/md0 /dev/sdd" because is telling me that the device is busy.

this RAID is giving me so many issues. i prefer to move to your idea geaves to use the two disk as individual and using rsync to have a backup data in the second drive.

Can you help me to move from RAID 1 to individual disk without losing any data or OMV configuration?

Many thanks.

Regards,

geaves · Sep 30th 2021

Quote from chuvihi

Can you help me to move from RAID 1 to individual disk without losing any data or OMV configuration

I read your previous thread here your last post would suggest there may be a hardware issue, either the sata cable, or the sata port the drive is connected too.

But to answer your question, under Raid Management select the array then click remove on the menu, remove one of the drives from the array and will leave the array in a clean/degraded state.

You will then need to wipe the drive you have removed, then create a file system.

Before you do any of that download and read this there is a section regarding rsync

chuvihi · Sep 30th 2021

Quote from geaves

I read your previous thread here your last post would suggest there may be a hardware issue, either the sata cable, or the sata port the drive is connected too.

But to answer your question, under Raid Management select the array then click remove on the menu, remove one of the drives from the array and will leave the array in a clean/degraded state.

You will then need to wipe the drive you have removed, then create a file system.

Before you do any of that download and read this there is a section regarding rsync

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Many thanks geaves. How then I can change from degraded raid to single disk without losing data or configuration? Now my nextcloud sync is not working due to the degraded raid.

Many thanks.

Regards,

geaves · Sep 30th 2021

Quote from chuvihi

How then I can change from degraded raid to single disk without losing data or configuration

You won't lose data, but you will have to reconfigure, all your shares are on your Raid, that's why I suggested looking at the hardware first.

Mirror RAID clean, degraded

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