Gfrktyl

I'm new to software RAID 1, hope I can seek some assistance in this forum.
My superior wish to have backup rather than soft RAID1.
How can I convert soft RAID 1 back to non RAID without any data lost

As below is fdisk -l command

Disk /dev/sdb: 500.1 GB, 500107862016 bytes, 976773168 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 4096 bytes

I/O size (minimum/optimal): 4096 bytes / 4096 bytes

Disk label type: dos

Disk identifier: 0x0009ab56



   Device Boot      Start         End      Blocks   Id  System

/dev/sdb1        16611328   879056895   431222784   fd  Linux raid autodetect

/dev/sdb2   *    15634432    16611327      488448   fd  Linux raid autodetect

/dev/sdb3            2048     7817215     3907584   fd  Linux raid autodetect

/dev/sdb4       879056896   976773119    48858112    5  Extended

/dev/sdb5       879058944   976773119    48857088   fd  Linux raid autodetect

Partition table entries are not in disk order

Disk /dev/sda: 500.1 GB, 500107862016 bytes, 976773168 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 4096 bytes

I/O size (minimum/optimal): 4096 bytes / 4096 bytes

Disk label type: dos

Disk identifier: 0x0009d585



   Device Boot      Start         End      Blocks   Id  System

/dev/sda1        16611328   879056895   431222784   fd  Linux raid autodetect

/dev/sda2   *    15634432    16611327      488448   fd  Linux raid autodetect

/dev/sda3            2048     7817215     3907584   fd  Linux raid autodetect

/dev/sda4       879056896   976773119    48858112    5  Extended

/dev/sda5       879058944   976773119    48857088   fd  Linux raid autodetect

Partition table entries are not in disk order

Disk /dev/md127: 3999 MB, 3999268864 bytes, 7811072 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 4096 bytes

I/O size (minimum/optimal): 4096 bytes / 4096 bytes





Disk /dev/md126: 50.0 GB, 49996103680 bytes, 97648640 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 4096 bytes

I/O size (minimum/optimal): 4096 bytes / 4096 bytes





Disk /dev/md125: 500 MB, 500105216 bytes, 976768 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 4096 bytes

I/O size (minimum/optimal): 4096 bytes / 4096 bytes





Disk /dev/md124: 441.4 GB, 441437913088 bytes, 862183424 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 4096 bytes

I/O size (minimum/optimal): 4096 bytes / 4096 bytes



and the details for df -TH

Filesystem     Type      Size  Used Avail Use% Mounted on

/dev/md126     xfs        47G   23G   24G  49% /

devtmpfs       devtmpfs   16G     0   16G   0% /dev

tmpfs          tmpfs      16G     0   16G   0% /dev/shm

tmpfs          tmpfs      16G   82M   16G   1% /run

tmpfs          tmpfs      16G     0   16G   0% /sys/fs/cgroup

/dev/md125     xfs       471M  202M  270M  43% /boot

tmpfs          tmpfs     3.2G     0  3.2G   0% /run/user/0

Thank you for your advice.

Kelvin

First off, you should back up your data - any kind of conversion should be considered high risk.... particularly when taking advice from someone you don't know on the Internet.

Once data is backed up, pull one of the disks (/dev/sdb preferably) from the array. This will cause the array to degrade, but will also make sure you have a copy of the data in case something goes wrong with the next step.

Ideally this should be done using from a USB boot disk, so nothing is live, but you might be able to do it from a live disk. Note that this will probably mean device ID's will change (ie /dev/sda may become /dev/sdb). Make sure you get the correct device identifiers and don't follow the below the blindly. Its important to understand each step.

using a partition editor, change the partition types for the RAID partitions from FD to 83 (ie Linux)

Modify /etc/fstab to point to /dev/sda? rather then UUID, or update the UUID's to match the underlying block device uuid - which you can find with "blkid /dev/sda?") [ If you are using a USB key, you will need to mount this first, so you may need to do something like

mount /dev/sdAX /mnt

then edit /mnt/etc/fstab

Remove the superblock (which will Delete the RAID blocks) with

mdadm --zero-superblock /dev/sda

Rerun grub -

grub-install /dev/sda