Poikilos indie game dev blog.

I was nervous about replacing the HDD (hard drive) containing BTRFS on root on my main computer with an SSD. However, remembered times when I was able to fix non-booting computers before using guides and sometimes help. I also felt better knowing I had a backup. Unlike Windows, a GNU+Linux operating system is not a "Humpty-Dumpty" system--you can be sure that if you have all of the files (not even boot partition files necessarily), there is a way to put it back together again. I've had more than a couple lengthy nightmare scenarios on Windows computers where no amount of refreshing, nor various boot repair commands, nor config file edits from forums including the Microsoft Support website did any good making Windows find the boot device again (even though everything was there!). The cause was usually a hard drive replacement or other system change. Explaining why Linux is better to certain customers or employers has been difficult. They tend to revert to the idea that I like it to "save money" no matter how much I explain it--people tend to erase their own experiences since Windows is popular and has more big companies supporting certain aspects of it. That is a whole separate topic, but it suffices to say that there are paid options for Linux in areas where it is lacking just like there are on Windows (including Windows Server). Since GNU+Linux is not a "Humpty-Dumpty" system, lets learn how to save the day and put a Linux system "back together again." If you are replacing your main hard drive which has BTRFS on root but EFI and SWAP are on separate partitions, you need to do some extra steps. Copying the three partitions changing the UID in fstab and grub.conf do not do it all. Updating or reinstalling GRUB won't do any good if you don't switch to the EFI version of the grub package (not grub-pc)! I found some advice on setting up my partitions this way, and the Debian 10 (Buster) ISO installed everything correctly (I switched to Devuan Chimera, but everything here still worked using a Debian 10 live CD to complete the setup of the destination drive). As for moving over to a new drive, there wasn't any direct advice. I used separate guides and some trial and error accomplish the task. Before starting: Follow steps in this article at your own risk. This article has no express or implied warranty or guarantee. Make a live DVD or CD (or USB if you don't have an optical drive) with Debian 10 (If your computer has Debian 10 or Devuan Chimera; otherwise use whatever ISO matches your system best). This guide assumes you have three partitions: /boot/efi (msdos), swap (swapfs), and / (BTRFS as the root filesystem--having subvolumes such as for home or other mount points is fine). Backup your old drive to a backup (third drive, not the new drive) with enough free space such as via: sudo mount /dev/sdbX /mnt/backup-drive where sdbX is the correct backup drive then sudo rsync -avPX --info=progress2 / /mnt/backup-drive/old-drive-slash sudo rsync -avPX --info=progress2 /boot/efi /mnt/backup-drive/old-drive-efi). You can backup your EFI partition and your BTRFS partition. If your backup drive is BTRFS, you can send a remote snapshot which is a nice way to do incremental backups (requires the btrfs-progs package). Note that experts have mixed opinions on using BTRFS on root, since only the core features of BTRFS are considered ready for daily use according to the kernel.org wiki, and the filesystem could be considered "perpetually half-finished" (whether that is relevant to any features used here is unclear--It seems only relevant to the snapshot and RAID features which aren't required for this guide). The kernel.org wiki recommends using the latest kernel when using BTRFS. (Optional unless you aren't sure how to ensure you have enough space) You can ensure you have the exact amount of space necessary as follows: Make sure the new drive is the same size as the old drive. Power off. Plug in the new (blank) drive and power on and log into the old OS. Ensure all programs are closed to avoid needing swap space. Open GParted. Note the partition sizes of the old drive. Right-click the old swap partition, click "Swapoff." Right-click it again, Copy. Select the new drive. If you can't create partitions and it says to create a filesystem, follow the instructions on screen and choose "GPT". The mountpoints don't matter yet--they will be defined in the configuration of the new copy of the drive, not here. Create an EFI partition of the same size (usually an easy even number) as the old drive's. Paste the swap partition. Create a new partition, choose BTRFS. Go back to the main drive. Right-click swap and choose "Swapon". (Optional) For extra certainty so you can tell which drive is which, you can power off, remove your backup drive then power on. To avoid files changing or becoming desynchronized from each other or from databases (usually not a significant problem except on servers, but filesystem- or database-heavy applications such as Nextcloud client may be affected), log into a TTY (text mode) rather than using the GUI login. Press Ctrl+Alt+3 (or change 3 to whatever TTY is unused) and login as root. If you are using a server, stop any services that may write to the disk heavily such as email, Nextcloud (Nextcloud server), web servers (Apache, NGINX), custom web applications, etc. Many of the commands require root privileges. If you are not logged in as root, type "sudo" before each command. Now that you have both drives installed, the old OS is booted, the new drive has the same partition layout, and you are logged in, you are ready. There is no need to recreate the BTRFS subvolumes since btrfs-replace will copy those automatically. In each command, change sda, sda3, sdb, sdb3 and '/' to the correct values for your system (old physical drive, old BTRFS partition, new physical drive, BTRFS partition on new drive, and mountpoint to migrate from the old to new partition, respectively). The steps assume you want a GPT filesystem and UEFI: If you use mbr and a BIOS boot partition, you will have to use grub-pc instead of grub-efi-amd64 and change the grub installation steps. (Those commands are based on Replacing an online drive with a bigger one from the BTRFS documentation but your new partition can be the same size.) Wait for the status command to inform you that the operation completed successfully before continuing! The btrfs replace start ... subcommand above will automatically change fstab, but assuming you have /boot/efi and swap on separate partitions, more steps are necessary. Even if they are not (swap can be in BTRFS, but must be on a separate subvolume to allow snapshots on the volume since it prevents snapshots on its own volume/subvolume), you still need to install grub on the new drive. Some people use the dd command for that, but I don't recommend that right now since reinstalling GRUB is easier: Reinstalling grub can detect your operating systems and generate grub.cfg automatically. The trailing slash in the command below is important: You don't need the copy to have /mnt/sdb1/efi/efi/EFI, but rather /mnt/sdb1/efi/EFI. Change the command below to the existing file. Run ls /mnt/sdb1/efi/EFI to see where your subdirectory is--In my case it was "debian" but it may be "grub" (The new one we'll install/reinstall will be "grub"). Boot from your live CD, DVD or USB (See "Before starting" above) to continue the rest of the steps--though if you don't get the dreaded "Boot Device Not Found" message or a similar error or didn't reboot you may be able to continue without it. Using it may change the drive letter(s) below (such as sda) so make sure to replace those with the correct ones by listing them with lsblk and blkid first! Using nano (or another editor), change the grub.cfg to use the UUID of the new drive's efi partition (sdb1 if using this guide), as listed by the blkid command. Use the short UUID (not the long PARTUUID). Press Ctrl+x to exit nano, then confirm save. If you did the btrfs replace ... subcommands above correctly, then '/' should now be mounted to the new drive. You must edit fstab to ensure the non-BTRFS partitions get mounted (prevent the dreaded "UUID=... does not exist." "A file system check failed" error that prevents boot; otherwise use the rescue prompt that error presents and login as root to continue). Compare the output above to the output of the blkid command. The UUID for the root filesystem "/" should already have been changed automatically by the first btrfs replace ... subcommand when it finished. Take note of the correct UUID for the swap and /boot/efi partitions. Using nano (or another editor), set the UUID for /boot/efi and the UUID for swap to match the new UUIDs for the first and second partitions on the new drive, respectively (such as listed for /dev/sdb1 and /dev/sdb3 using the blkid command, or possibly /dev/sda1 and /dev/sda3 if you rebooted without the old drive--the number(s) will differ if using a different layout than this guide uses, and the last letter of each will differ if drives are recognized by linux in a different order). Now you must install grub onto /dev/sdb (It may be /dev/sda if you are using a removable boot drive. The last letter will differ if drives are recognized by linux in a different order). (The set of commands below is based on roadmr's Jun 1, 2012 answer edited Jun 2, 2012 on How do I run update-grub from a LiveCD? on StackExchange) You may need to install grub (fixes the error grub-install: command not found). You should do sudo apt-get install grub-efi-amd64 (not grub-pc) to work with EFI (according to Rod Smith's Apr 18, 2015 answer on grub2-install: "this GPT partition label contains no BIOS Boot Partition" on StackExchange). According to How to Install GRUB2 with EFI Support by LinuxLink (if your OS is 32-bit see the instructions there for 32-bit which differ!), you can install grub with EFI compatibility with the following two commands. Make sure...

Poikilos indie game dev blog.

Replace your BTRFS on root and reinstall EFI grub on the new drive.