Missing/inactive RAID array [SOLVED]

Hello,

I have a 3 x 2TB RAID5 array in a NAS which has stopped working for unknown reasons.

I can think of 2 possible causes:

a couple of days ago I noticed the SATA cable for /dev/sdd had come loose. I reconnected it and carried on. The RAID seemed OK

I have been changing the BIOS settings on my NAS - this was immediately prior to the RAID array not appearing on the OpenMediaVault control panel

My RAID is made up of 3 devices /dev/sdb /dev/sdc /dev/sdd

/dev/sdd is still part of the array but the other 2 devices are not and I cannot add them back in with mdadm --assemble

I will be EXTREMELY grateful for any help as I have no backups!!

Looking at the output from fdisk I have noticed that /dev/sdb and /dev/sdc have a lower (but identical) sector count than /dev/sdd - sdb and sdc have 2,113 fewer sectors - I do not understand why or if this is even relevant.

Here is some info:

root@mother:~# cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] 
md0 : inactive sdd[0]
      1953382488 blocks super 1.2
       
unused devices: <none>

root@mother:~# blkid
/dev/sdc: UUID="00218694-5b9b-a78a-a048-e32b074fdc6e" UUID_SUB="540d2196-c0a8-ecc2-9c35-4c5572388e62" LABEL="mother:raid1" TYPE="linux_raid_member"
/dev/sdb: UUID="00218694-5b9b-a78a-a048-e32b074fdc6e" UUID_SUB="b3980495-0904-48ba-6937-a88a40e83b31" LABEL="mother:raid1" TYPE="linux_raid_member"
/dev/sda1: UUID="e624a0e5-df0d-4508-8a6c-af88d7afabda" TYPE="ext4" PARTUUID="11275e1b-01"
/dev/sda5: UUID="bf9dc110-a5a3-4d13-b122-69882c1547c8" TYPE="swap" PARTUUID="11275e1b-05"
/dev/sdd: UUID="00218694-5b9b-a78a-a048-e32b074fdc6e" UUID_SUB="c7aeb61c-4050-2e8c-c803-093f94d9cb3f" LABEL="mother:raid1" TYPE="linux_raid_member"

root@mother:~# fdisk -l | grep "Disk "
Disk /dev/sdc: 1.8 TiB, 2000397852160 bytes, 3907027055 sectors
Disk model: ST2000DM006-2DM1
Disk /dev/sdb: 1.8 TiB, 2000397852160 bytes, 3907027055 sectors
Disk model: ST2000DM008-2FR1
Disk /dev/sda: 223.6 GiB, 240056327680 bytes, 468860015 sectors
Disk model: GIGABYTE GP-GSTF
Disk identifier: 0x11275e1b
Disk /dev/sdd: 1.8 TiB, 2000398934016 bytes, 3907029168 sectors
Disk model: ST2000DM008-2FR1

root@mother:~# cat /etc/mdadm/mdadm.conf 
# This file is auto-generated by openmediavault (https://www.openmediavault.org)
# WARNING: Do not edit this file, your changes will get lost.

# 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=mother:raid1 UUID=00218694:5b9ba78a:a048e32b:074fdc6e

root@mother:~# mdadm --detail --scan --verbose
INACTIVE-ARRAY /dev/md0 level=raid5 num-devices=3 metadata=1.2 name=mother:raid1 UUID=00218694:5b9ba78a:a048e32b:074fdc6e
   devices=/dev/sdd

I have found a post relating to someone losing sectors on their HDD:

Interestingly - the numbers exactly match what has happened to my two drives. And they have a Gigabyte motherboard - I do too.

here is some info:

root@mother:~# hdparm -N /dev/sdb
/dev/sdb:
 max sectors   = 3907027055/3907029168, HPA is enabled

root@mother:~# hdparm -N /dev/sdc
/dev/sdc:
 max sectors   = 3907027055/3907029168, HPA is enabled

root@mother:~# hdparm -N /dev/sdd
/dev/sdd:
 max sectors   = 3907029168/3907029168, HPA is disabled
root@mother:~# 

In other words, my Gigabyte motherboard has enabled HPA on two of the 3 disks.

So, I think this explains why I have "lost" sectors on sdb and sdc.

Should I use

hdparm -N p3907029168 /dev/sdb
hdparm -N p3907029168 /dev/sdc

to disable HPA and get back the lost sectors? Also is that the correct syntax for hdparm?

So, my plan is to use hdparm to disable HPA and then try to re-assemble the array using mdadm.

Before I do so I would like to hear what you guys think.

many thanks.

I'm delighted to report that I have re-assembled my RAID!!!

HPA was removed from sdb and sdc to give the following:

root@mother:~# hdparm -N /dev/sdb
/dev/sdb:
max sectors   = 3907029168/3907029168, HPA is disabled

root@mother:~# hdparm -N /dev/sdc
/dev/sdc:
max sectors   = 3907029168/3907029168, HPA is disabled

root@mother:~# hdparm -N /dev/sdd
/dev/sdd:
 max sectors   = 3907029168/3907029168, HPA is disabled

Then all I had to do was reboot openmediavault and /dev/md0 (the RAID array) was good to go.

I'm incredibly relieved. Cheers everyone.

Zitat

And now you know the value of backups and might make some

I'm already working on it!! The ironic thing is this all happened trying to add more SATA ports to the motherboard - in order to back-up the RAID!!

Anyway I am very happy right now.