Gfilui

I ordered new Debian web server which has 2 hard disks. I assume that one of them should be partitioned and mounted. The problem is that I cannot identify which one should be partitioned and mounted and which one has all the Ubuntu files. Here are the results of several commands which I could not get the answer, perhaps due to lack of knowledge in Ubuntu.

# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 477G 0 disk
├─sda1 8:1 0 32G 0 part
│ └─md0 9:0 0 32G 0 raid1 [SWAP]
├─sda2 8:2 0 512M 0 part
│ └─md1 9:1 0 511.4M 0 raid1 /boot
└─sda3 8:3 0 444.4G 0 part
 └─md2 9:2 0 444.3G 0 raid1 /
sdb 8:16 0 477G 0 disk
├─sdb1 8:17 0 32G 0 part
│ └─md0 9:0 0 32G 0 raid1 [SWAP]
├─sdb2 8:18 0 512M 0 part
│ └─md1 9:1 0 511.4M 0 raid1 /boot
└─sdb3 8:19 0 444.4G 0 part
 └─md2 9:2 0 444.3G 0 raid1 /


# fdisk -l

Disk /dev/sdb: 477 GiB, 512110190592 bytes, 1000215216 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x0ba4900f

Device Boot Start End Sectors Size Id Type
/dev/sdb1 2048 67110911 67108864 32G fd Linux raid autodetect
/dev/sdb2 67110912 68159487 1048576 512M fd Linux raid autodetect
/dev/sdb3 68159488 1000213167 932053680 444.4G fd Linux raid autodetect

Disk /dev/sda: 477 GiB, 512110190592 bytes, 1000215216 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x31fd01ce

Device Boot Start End Sectors Size Id Type
/dev/sda1 2048 67110911 67108864 32G fd Linux raid autodetect
/dev/sda2 67110912 68159487 1048576 512M fd Linux raid autodetect
/dev/sda3 68159488 1000213167 932053680 444.4G fd Linux raid autodetect

Disk /dev/md0: 32 GiB, 34326183936 bytes, 67043328 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/md1: 511.4 MiB, 536281088 bytes, 1047424 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/md2: 444.3 GiB, 477077241856 bytes, 931791488 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


# blkid
/dev/sdb1: UUID="4374a69b-c5ca-ceee-bfd3-3df61d255a13" UUID_SUB="f1ca2293-d87d-83b8-dad9-aba968c25d0a" LABEL="rescue:0" TYPE="linux_raid_member" PARTUUID="0ba4900f-01"
/dev/sdb2: UUID="4b93d869-e581-7187-70ca-c4f9e7668ed5" UUID_SUB="6921e275-a6f3-0e5f-52c6-37520265266e" LABEL="rescue:1" TYPE="linux_raid_member" PARTUUID="0ba4900f-02"
/dev/sdb3: UUID="10c95f64-534c-e940-f016-77851637282b" UUID_SUB="003339b6-34c6-a11c-0f95-722934e2cd25" LABEL="rescue:2" TYPE="linux_raid_member" PARTUUID="0ba4900f-03"
/dev/sda1: UUID="4374a69b-c5ca-ceee-bfd3-3df61d255a13" UUID_SUB="865a9479-0077-b93e-fde5-62b4427eed93" LABEL="rescue:0" TYPE="linux_raid_member" PARTUUID="31fd01ce-01"
/dev/sda2: UUID="4b93d869-e581-7187-70ca-c4f9e7668ed5" UUID_SUB="fade36f5-1a58-9645-4c8e-d3bbbadb2d4d" LABEL="rescue:1" TYPE="linux_raid_member" PARTUUID="31fd01ce-02"
/dev/sda3: UUID="10c95f64-534c-e940-f016-77851637282b" UUID_SUB="75c16690-bce6-0f66-1a6f-4819b70fb1bd" LABEL="rescue:2" TYPE="linux_raid_member" PARTUUID="31fd01ce-03"
/dev/md0: UUID="2317882d-d15e-4879-8eab-8d37b77b717e" TYPE="swap"
/dev/md1: UUID="6ef84344-8aa2-4807-9486-4c98ab3aeffa" TYPE="ext3"
/dev/md2: UUID="a710dcc5-e25f-452b-bffd-486bb9eba812" TYPE="ext4"

Both are mounted simultaneously. That is because they are both part of a single RAID1 disk array, which is referenced as /dev/md0,1,2 for the actual 'partitions' being used for the actual 'devices' which store disk data (for /boot, /, swap space, etc.)

This is a setup where you're using mdadm or such and have the two drives together as part of a software-based RAID1 array. That's why you see in fdisk -l the "Linux raid autodetect" filesystem type.

The two disks are 'identical' because of the RAID1 restriction on mapped disk space - you'd need two identical disks to get true RAID1, and that's what you have here. (And though this is not true RAID which is done at the hardware level with RAID controllers, this is a software-driven RAID array that achieves the same type of setup).