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andromeda87

Member

Registered: 2024-03-08

Posts: 4

BTRFS moving root issues

Hello everyone!

I recently bought a new gen5 drive and thought I'd move over the filesystem over to the gen5, which worked great, but since I now have an extra gen4 I thought I'd keep the /efi and /root on that one and only wanted to have /home on gen5.

Currently where I have gotten to is as you can see below:

>lsblk -f
NAME        FSTYPE FSVER LABEL    UUID                                 FSAVAIL FSUSE% MOUNTPOINTS
nvme1n1                                                                               
├─nvme1n1p1 vfat   FAT32          9012-1354                             414.1M    19% /efi
└─nvme1n1p2 btrfs        archroot d9094d69-28a4-4cf8-af1e-9f1966c6efcb
nvme0n1                                                                               
└─nvme0n1p1 btrfs        system   7cafcdd0-7e9b-4d64-a25d-b93ccf5ac48f  311.1G    83% /home
                                                                                      /

so as you can see I have efi on gen4 but both /root and /home on the new gen5. I did the below to move the /root to nvme1n1p2 but it didn't work and came back to the same setup as before.

# create mount points
mkdir -p /mnt/gen5 /mnt/gen4
mount /dev/nvme0n1p1 /mnt/gen5
mount /dev/nvme1n1p2 /mnt/gen4

# snapshot
btrfs subvolume snapshot -r /mnt/gen5/@ /mnt/gen5/@_snap
btrfs send /mnt/old_fs/@_snap | btrfs receive /mnt/gen4
btrfs subvolume snapshot /mnt/gen4/@_snap /mnt/gen4/@

# clean up snapshots
btrfs subvolume delete /mnt/gen5/@_snap
btrfs subvolume delete /mnt/gen4/@_snap

# remount drives
umount -R /mnt
mount -o compress=zstd,subvol=@ /dev/nvme1n1p1 /mnt
mkdir -p /mnt/home /mnt/efi
mount -o compress=zstd,subvol=@home /dev/nvme0n1p2 /mnt/home
mount /dev/nvme1n1p1 /mnt/efi

# genfstab
genfstab -U /mnt > /mnt/etc/fstab

# arch-chroot
arch-chroot /mnt
grub-mkconfig -o /boot/grub/grub.cfg
exit
umount -R /mnt
reboot now

What could I have done differently to get the outcome I would like, I would prefer the outcome not needing to delete the existing root on nvme0n1p1 until I can see it working first.

ua4000

Member

Registered: 2015-10-14

Posts: 526

Re: BTRFS moving root issues

I thought I'd keep the /efi and /root on that one and only wanted to have /home on gen5.

With gen4 and 5 you refer to an NVME with PCIe 4 or 5 ?
Your idea makes no sense.
Use the fastest one (gen5) for efi, boot, root, home (app settings/profile) - this is the one which impacts you on machine start, app start, daily usage.
Use the slower (older!) one (gen4) for additional data storage (videos, pictures) or as mirror / backup.