Migration to SSD and reconfig of filesystem setup

I was finally about to migrate to a SSD on my laptop when I started to think about switching to Btrfs and getting rid of LVM while I’m at it. To achieve that I tried different things but came down to the following. At this point I also had the SSD installed in my laptop already and the old HDD pluggable with SATA-to-USB adapter.

Basic idea: Via live usb, create /boot and LUKS container (with /) on SSD. Format / and /boot to Btrfs. Migrate data with rsync. Do the usual steps at the end of an arch installation (fstab, bootloader, mkinitcpio etc).

Detailed steps: (based on ArchWiki:Dm-crypt-Encrypting an entire system)

• fdisk /dev/sdSSD and create new MBR (DOS) table (because BIOS booting on my x220 doesn’t work with GPT). Create /boot partition for grub (in my case 350MiB, here /dev/sdSSD1) and / (rest of space, here /dev/sdSSD2), both of type linux file system. Mark /boot bootable.
• Setup LUKS container: (DISCLAIMER: Thats important, please read the arch wiki before deciding on your parameters: ArchWiki:Dm-crypt-Encryption options for LUKS mode )
  • cryptsetup --key-size 512 --hash sha512 --iter-time 5000 luksFormat /dev/sdSSD2
  • Verify with cryptsetup luksOpen /dev/sdSSD2 cryptroot. Now that partition is also mapped and available for formatting continue with the following.
• Format mkfs.btrfs -L root /dev/mapper/cryptroot and mount mount -o compress=lzo /dev/mapper/cryptroot /mnt. More on compression: ArchWiki:Btrfs
• Next is creating subvolumes which will replace classic partitions in this setup. I’m new to Btrfs and just know the basics. There is more information here: ArchWiki:Dm-crypt-Encrypting an entire system
  • btrfs subvolume create /mnt/@ and same with /mnt/@snapshots and /mnt/@home
• Now with everything setup for / next step is copying the data.
  • Unmount unmount /mnt and mount new “real” root mount -o compress=lzo,subvol=@ /dev/mapper/cryptroot /mnt
  • Plug in old HDD. cryptsetup luksOpen /dev/sdHDD2 oldroot and mkdir /mntOld to mount /dev/mapper/vg-root /mntOld (my old setup had root, home and swap at this LVM layer).
  • Copy data from old disk to new. Attention: one little trailing / gave me some headache (1) until I executed rsync the following way.
  • rsync -aAXHs --numeric-ids --info=progress2 --exclude={"/dev/*","/proc/*","/sys/*","/tmp/*","/run/*","/mnt/*","/media/*","/lost+found",”/var/cache/pacman/pkg/*”} /mntOld/ /mnt
  • Almost same for /home: umount /mnt and same for /mntOld
  • mount -o compress=lzo,subvol=@home /dev/mapper/cryptroot /mnt and mount /dev/mapper/vg-home /mntOld
  • rsync -aAXHs --numeric-ids --info=progress2 --exclude={"/lost+found",”*/.thumbnails/*”,”*/.cache/mozilla/*”,”*/.cache/chromium/*”,”*/.local/share/Trash/*”,”*/.gvfs”} /mntOld/ /mnt
• Preparing and installing bootloader to /boot.
  • Because I was using syslinux and learned while reading the wiki and documentation that it doesn’t support compressed Btrfs. I just installed GRUB as new bootloader. This seems to be a good idea anyway because Syslinux wasn’t updated in quite a while. In many situations keeping the bootloader might work just fine. But if you choose the apadt another one remember to migrate hooks etc too.
  • umount /mnt and umount /mntOld
  • mkfs.btrfs -L boot /dev/sdSSD1
  • Finally mount the almost ready system
    • mount -o compress=lzo,subvol=@ /dev/mapper/cryptroot /mnt
    • mount -o compress=lzo,subvol=@home /dev/mapper/cryptroot /mnt/home
    • mount -o compress=lzo,subvol=@snapshots /dev/mapper/cryptroot /mnt/.snapshots
    • mount -o compress=lzo /dev/sdSSD1 /mnt/boot
    • Update filesystem table genfstab -U /mnt >> /mnt/etc/fstab. Modify with editor so old lines are commented or removed.
  • Config internet access on live system and chroot into new system arch-chroot /mnt /bin/zsh
    • Install grub package and install grub itself grub-install --target=i386-pc /dev/sdSSD (important to address whole disk here so GRUB can be written into MBR)
    • Edit /etc/default/grub: modify line to GRUB_CMDLINE_LINUX="cryptdevice=/dev/sda2:cryptroot:allow-discards" (discarding is necessary for SSD trimming later) and uncomment GRUB_ENABLE_CRYPTODISK=y line.
    • Edit mkinitcpio.conf: check or modify lines MODULES=”btrfs” and BINARIES="/usr/bin/btrfs"; check if encrypt hook and everything else needed is there. Remove lvm2 hook.
    • Reinstall linux pacman -S linux to get necessary files and start mkinitcpio. Image generation must be successful!
    • Write changes grub-mkconfig -o /boot/grub/grub.cfg to GRUB. You should see messages of found images.
  • Last but not least: config SSD behavior
    • TLP config: check or modify line to SATA_LINKPWR_ON_BAT=max_performance
    • LUKS parameter was given above already (:allow-discards).
    • Enable weekly trimming systemctl enable fstrim.timer.
  • exit chroot. Cleanly unmount everything umount -R /mnt and reboot.

Everything should work now. Additionally I removed pacman -Rs hdapsd shock protection for mechanical disk because that’s obviously not necessary anymore.

Last friendly disclaimer: The way I described above is just the way I fiddled for my specific situation. Sadly I’m just a linux enthusiast and not an expert so there might be design flaws or other errors included.