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I have a btrfs filesystem mount as / (root) and /home. I have two drives in my filesystem,

    Total devices 2 FS bytes used 233.79GiB
    devid    1 size 922.51GiB used 115.00GiB path /dev/sda3
    devid    2 size 931.51GiB used 123.03GiB path /dev/sdb1

/dev/sdb1 is an SSD and /dev/sda3 is a normal HDD.

To my untrained eye, it looks like both these volumes are spread across both disks

$ sudo btrfs device usage /home
/dev/sda3, ID: 1
   Device size:           922.51GiB
   Device slack:              0.00B
   Data,single:           108.00GiB
   Metadata,single:         7.00GiB
   Unallocated:           807.51GiB

/dev/sdb1, ID: 2
   Device size:           931.51GiB
   Device slack:              0.00B
   Data,single:           121.00GiB
   Metadata,single:         2.00GiB
   System,single:          32.00MiB
   Unallocated:           808.48GiB

$ sudo btrfs device usage /
/dev/sda3, ID: 1
   Device size:           922.51GiB
   Device slack:              0.00B
   Data,single:           108.00GiB
   Metadata,single:         7.00GiB
   Unallocated:           807.51GiB

/dev/sdb1, ID: 2
   Device size:           931.51GiB
   Device slack:              0.00B
   Data,single:           121.00GiB
   Metadata,single:         2.00GiB
   System,single:          32.00MiB
   Unallocated:           808.48GiB

I can't seem to find a command that will definitively show how the two directories (subvolumes?) are spread across the drives.

So my question. Is there a way to force /home to reside on one disk and / to reside on the other.

Thx.

ScaryAardvark
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    "Is there a way…?" – Yes. Two separate BTRFS filesystems, each on its own device. – Kamil Maciorowski May 31 '18 at 07:27
  • To guide you we need the output of the following commands: btrfs fi df /, df / /home, lsblk, grep -E 'btrfs|/boot' /etc/fstab, mount | grep -E 'btrfs|/boot'. Are there other subvolumes in the BTRFS filesystem? Which device holds the primary bootloader? Any quirks you are aware of? (like mounting via systemd, beyond fstab etc.) – Kamil Maciorowski May 31 '18 at 07:58
  • Can you not add and remove respective devices to each subvolume? The data should be moved to the correct place. I would recommend backing up the lot before trying anything. – Ken Sharp Nov 19 '19 at 00:48

0 Answers0