Bsrgvty

This is not an urgent problem, but I would like to know if I am currently making use of both of my hard drives (and/or if I can fix that).

Essentially, I purchased this computer without an OS and I have successfully installed Ubuntu Server on it.

The computer comes with 2 3TB hard drives.

My understanding is that I can either have a RAID0 configuration to have 6 TB of storage space, or a RAID1 configuration where 1 3 TB drive mirrors the other 3 TB drive.

Given that I have started to run analysis on the server, I am OK with mirroring the hard drive (RAID1).

However, I don't think I have successfully done that. For example, if I check my /proc/mdstat file, this is what it says:

Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10]
md126 : active raid1 sda[1] sdb[0]
 2930264064 blocks super external:/md127/0 [2/2] [UU]

md127 : inactive sda[1](S) sdb[0](S)
 5040 blocks super external:imsm

unused devices: <none>

Likewise, this how those drives are recognized using lsblk -o NAME,SIZE,FSTYPE,TYPE,MOUNTPOINT

NAME SIZE FSTYPE TYPE MOUNTPOINT
sda 2.7T isw_raid_member disk
└─md126 2.7T raid1
 ├─md126p1 512M vfat md /boot/efi
 └─md126p2 2.7T ext4 md /
sdb 2.7T isw_raid_member disk
└─md126 2.7T raid1
 ├─md126p1 512M vfat md /boot/efi
 └─md126p2 2.7T ext4 md /
sr0 1024M rom

However, this is the available space that I have using df:

Filesystem 1K-blocks Used Available Use% Mounted on
udev 16370772 0 16370772 0% /dev
tmpfs 3280440 940 3279500 1% /run
/dev/md126p2 2882700496 223265236 2512931992 9% /
tmpfs 16402180 0 16402180 0% /dev/shm
tmpfs 5120 0 5120 0% /run/lock
tmpfs 16402180 0 16402180 0% /sys/fs/cgroup
/dev/md126p1 523248 6152 517096 2% /boot/efi
tmpfs 3280436 0 3280436 0% /run/user/1000

So, my questions are as follows:

1. 
   

   Am I actually mirroring my hard drive with a RAID1 configuration?
   
   If so, how can I recover my hard drive is something goes wrong?

   
   
   

   From the /proc/mdstat file, it looks like there is some sort of the link between the drives (since md126 is listed with super external:/md127/0, on the 2nd line)

   
   



2. If both hard drives are not currently being used (for RAID1 mirroring), what do I need to change? Can I start mirroring my first hard drive without erasing everything currently on the first drive?

While I haven't finished taking the class(es), I have some other notes that I thought might be good to add:

Comment/Update #2
(Comment / Update #1 is an "Answer")

1) You can see the following information with sudo fdisk -l:

Disk /dev/sda: 2.7 TiB, 3000592982016 bytes, 5860533168 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
Disklabel type: gpt
Disk identifier: xxxxxxxx:xxxxxxxx:xxxxxxxx:xxxxxxxx

Device Start End Sectors Size Type
/dev/sda1 2048 1050623 1048576 512M EFI System
/dev/sda2 1050624 5860526079 5859475456 2.7T Linux filesystem

Disk /dev/sdb: 2.7 TiB, 3000592982016 bytes, 5860533168 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
Disklabel type: gpt
Disk identifier: xxxxxxxx:xxxxxxxx:xxxxxxxx:xxxxxxxx

Device Start End Sectors Size Type
/dev/sdb1 2048 1050623 1048576 512M EFI System
/dev/sdb2 1050624 5860526079 5859475456 2.7T Linux filesystem

Disk /dev/md126: 2.7 TiB, 3000590401536 bytes, 5860528128 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
Disklabel type: gpt
Disk identifier: xxxxxxxx:xxxxxxxx:xxxxxxxx:xxxxxxxx

Device Start End Sectors Size Type
/dev/md126p1 2048 1050623 1048576 512M EFI System
/dev/md126p2 1050624 5860526079 5859475456 2.7T Linux filesystem

Since this already says that /dev/sdb is a Linux file system, I think that part is OK.

For posting on-line, I set the UUIDs to be "xxxxxxxx:xxxxxxxx:xxxxxxxx:xxxxxxxx", but I otherwise have provided the exact output.

2) While I want to be cautious, I think the next step involves the command mkfs.ext4. However, I want to be careful and learn more before I do something that may (or may not) affect my current file system.

If I try to use the mount command, then this is what I currently see:

$:/mnt$ sudo mount /dev/sda1 /mnt/test1
mount: /mnt/test1: special device /dev/sda1 does not exist.
$:/mnt$ sudo mount /dev/sda2 /mnt/test1
mount: /mnt/test1: special device /dev/sda2 does not exist.
$:/mnt$ sudo mount /dev/sdb1 /mnt/test1
mount: /mnt/test1: /dev/sdb1 already mounted or mount point busy.
$:/mnt$ sudo mount /dev/sdb2 /mnt/test1
mount: /mnt/test1: /dev/sdb2 already mounted or mount point busy.

FYI, I previously learned about fdisk, but I didn't see that in the earlier notes. Otherwise, I added new notes from the following class(es):

https://www.linkedin.com/learning/building-an-ubuntu-home-server/add-storage-with-a-local-disk

It's still not exactly an answer. However, if I use the MD administration function mdadm, then I can see the following information:

I believe this is for the 1st RAID hardrive:

$ sudo mdadm --detail /dev/md126
/dev/md126:
 Container : /dev/md/imsm0, member 0
 Raid Level : raid1
 Array Size : 2930264064 (2794.52 GiB 3000.59 GB)
 Used Dev Size : 2930264064 (2794.52 GiB 3000.59 GB)
 Raid Devices : 2
 Total Devices : 2

 State : active
 Active Devices : 2
 Working Devices : 2
 Failed Devices : 0
 Spare Devices : 0

Consistency Policy : resync


 UUID : xxxxxxxx:xxxxxxxx:xxxxxxxx:xxxxxxxx
 Number Major Minor RaidDevice State
 1 8 0 0 active sync /dev/sda
 0 8 16 1 active sync /dev/sdb
$ sudo mdadm --detail /dev/md126p1
/dev/md126p1:
 Container : /dev/md/imsm0, member 0
 Raid Level : raid1
 Array Size : 524288 (512.00 MiB 536.87 MB)
 Used Dev Size : 18446744073709551615
 Raid Devices : 2
 Total Devices : 2

 State : active
 Active Devices : 2
 Working Devices : 2
 Failed Devices : 0
 Spare Devices : 0

Consistency Policy : resync


 UUID : xxxxxxxx:xxxxxxxx:xxxxxxxx:xxxxxxxx
 Number Major Minor RaidDevice State
 1 8 0 0 active sync /dev/sda
 0 8 16 1 active sync /dev/sdb

$ sudo mdadm --detail /dev/md126p2
/dev/md126p2:
 Container : /dev/md/imsm0, member 0
 Raid Level : raid1
 Array Size : 2929737728 (2794.02 GiB 3000.05 GB)
 Used Dev Size : 2930264064 (2794.52 GiB 3000.59 GB)
 Raid Devices : 2
 Total Devices : 2

 State : clean
 Active Devices : 2
 Working Devices : 2
 Failed Devices : 0
 Spare Devices : 0

Consistency Policy : resync


 UUID : xxxxxxxx:xxxxxxxx:xxxxxxxx:xxxxxxxx
 Number Major Minor RaidDevice State
 1 8 0 0 active sync /dev/sda
 0 8 16 1 active sync /dev/sdb

and I believe this is for the 2nd RAID harddrive:

$ sudo mdadm --detail /dev/md127
/dev/md127:
 Version : imsm
 Raid Level : container
 Total Devices : 2

 Working Devices : 2


 UUID : xxxxxxxx:xxxxxxxx:xxxxxxxx:xxxxxxxx
 Member Arrays : /dev/md/Volume1

 Number Major Minor RaidDevice

 - 8 0 - /dev/sda
 - 8 16 - /dev/sdb

Otherwise, I guess the RAID1 configuration is set up (and that is what md126p1 and md126p2 stand for)?

For example, it does say Raid Level : raid1 for the 1st drive, although I wonder why it doesn't say that for the 2nd drive

For posting on-line, I set the UUIDs to be "xxxxxxxx:xxxxxxxx:xxxxxxxx:xxxxxxxx", but I otherwise have provided the exact output.

There are also 4 other files where I can look up additional information, including the "Volume1" that I believe refers to the 2nd drive?

$ ls /dev/md/
imsm0 Volume1 Volume1p1 Volume1p2
~$ sudo mdadm --detail /dev/md/Volume1
/dev/md/Volume1:
 Container : /dev/md/imsm0, member 0
 Raid Level : raid1
 Array Size : 2930264064 (2794.52 GiB 3000.59 GB)
 Used Dev Size : 2930264064 (2794.52 GiB 3000.59 GB)
 Raid Devices : 2
 Total Devices : 2

 State : active
 Active Devices : 2
 Working Devices : 2
 Failed Devices : 0
 Spare Devices : 0

Consistency Policy : resync


 UUID : xxxxxxxx:xxxxxxxx:xxxxxxxx:xxxxxxxx
 Number Major Minor RaidDevice State
 1 8 0 0 active sync /dev/sda
 0 8 16 1 active sync /dev/sdb

There are also mdadm --create, mdadm --grow, and mdadm --incremental functions.

FYI, I decided to add these notes after taking this class: https://www.udemy.com/course/the-complete-ubuntu-linux-server-administration-course/