This is what I've figured out to get a btrfs partition on a single disk. I use a hook script to get a btrfs on /home. I'm posting this in case someone else needs it.
disk_config disk1 disklabel:gpt fstabkey:uuid align-at:1M # EFI system partition p=efi /boot/efi 512M vfat rw # /boot separate so bootloader doesn’t depend on Btrfs p=boot /boot 500M ext4 rw,noatime # Main Btrfs volume (everything else) p=btrfs / 4G- btrfs subvol=@,defaults,noatime,autodefrag,compress=zstd ------script----- [root@fai:/srv/fai/config/scripts/EFI_BTRFS_SEPARATE_HOME]# cat 10-btrfs-setup #!/bin/bash set -e # Create disk2 manually parted -s /dev/sdb mklabel gpt parted -s /dev/sdb mkpart homefs btrfs 1MiB 100% # Format mkfs.btrfs -f /dev/sdb1 # Create subvolume mount /dev/sdb1 /mnt btrfs subvolume create /mnt/@home umount /mnt # Mount in target dir tree mkdir -p /target/home mount -o subvol=@home,compress=zstd /dev/sdb1 /target/home # Get the UUID for fstab entry UUID=$(blkid -s UUID -o value /dev/sdb1) # Add fstab entry to the installed system echo "UUID=$UUID /home btrfs subvol=@home,defaults,noatime,autodefrag,compress=zstd 0 0" >> /target/etc/fstab Neil Thackeray Sr. Systems Engineer Beckman Institute for Advanced Science and Technology University of Illinois at Urbana-Champaign 405 N. Mathews Avenue | M/C 251 Urbana, IL 61801 217.244.3283 |[email protected]<mailto:[email protected]> beckman.illinois.edu<http://beckman.illinois.edu> <https://urldefense.proofpoint.com/v2/url?u=https-3A__www.facebook.com_BeckmanInstitute_&d=DwMFAg&c=Y6HT0gyZH_Z4ZSRJdNYJeQ&r=E6prYDpN9ussAIJLh2x38kaf4YVwMm8ZX5bJ1PbLZBs&m=OxRN37707WnlwC204YOrBJZdsW_C4qZrsu2FavQfY6M&s=ekONmaVvkPGjvXVPjR0stKxfOLT2b-QFzd9YwWyG8vI&e=> [twitter] <https://urldefense.proofpoint.com/v2/url?u=https-3A__twitter.com_beckmaninst&d=DwMFAg&c=Y6HT0gyZH_Z4ZSRJdNYJeQ&r=E6prYDpN9ussAIJLh2x38kaf4YVwMm8ZX5bJ1PbLZBs&m=OxRN37707WnlwC204YOrBJZdsW_C4qZrsu2FavQfY6M&s=OJLVpqOnsiXzlPY-KldMY-hcap7hI0tYvOzkR0DFhSQ&e=> [instagram] <https://urldefense.proofpoint.com/v2/url?u=https-3A__www.instagram.com_beckmaninstitute_&d=DwMFAg&c=Y6HT0gyZH_Z4ZSRJdNYJeQ&r=E6prYDpN9ussAIJLh2x38kaf4YVwMm8ZX5bJ1PbLZBs&m=OxRN37707WnlwC204YOrBJZdsW_C4qZrsu2FavQfY6M&s=UT-VJjEZ33GWTerFJWUEyBYdfRh6MB0Eiwy55sCstqc&e=> [linkedin] <https://urldefense.proofpoint.com/v2/url?u=https-3A__www.linkedin.com_showcase_beckman-2Dinstitute-2Dat-2Dillinois&d=DwMFAg&c=Y6HT0gyZH_Z4ZSRJdNYJeQ&r=E6prYDpN9ussAIJLh2x38kaf4YVwMm8ZX5bJ1PbLZBs&m=OxRN37707WnlwC204YOrBJZdsW_C4qZrsu2FavQfY6M&s=Pf-ARQKk_qKEjhaHfMY1Mf7b-CkzcnssC4faEN_Glus&e=> [youtube] <https://urldefense.proofpoint.com/v2/url?u=https-3A__www.youtube.com_user_BeckmanInstitute&d=DwMFAg&c=Y6HT0gyZH_Z4ZSRJdNYJeQ&r=E6prYDpN9ussAIJLh2x38kaf4YVwMm8ZX5bJ1PbLZBs&m=OxRN37707WnlwC204YOrBJZdsW_C4qZrsu2FavQfY6M&s=dTbGx8NfqndFUfasHWaLCrAtX-aax1RWhuHMAeQ6Aus&e=> [https://webservices.illinois.edu/webservices/public/ds/signature_logo.png]<https://urldefense.proofpoint.com/v2/url?u=http-3A__illinois.edu_&d=DwMFAg&c=Y6HT0gyZH_Z4ZSRJdNYJeQ&r=E6prYDpN9ussAIJLh2x38kaf4YVwMm8ZX5bJ1PbLZBs&m=OxRN37707WnlwC204YOrBJZdsW_C4qZrsu2FavQfY6M&s=aluvB_9OTwFeHP1WVF4NsF1o2_LYpK8gLodBttru3JY&e=> Under the Illinois Freedom of Information Act, any written communication to or from university employees regarding university business is a public record and may be subject to public disclosure. ________________________________ From: linux-fai <[email protected]> on behalf of Thackeray, Neil L <[email protected]> Sent: Friday, October 31, 2025 4:50 PM To: fully automatic installation for Linux <[email protected]> Subject: Re: BTRFS LVM EFI config Am I wrong in thinking that doing btrs with LVM is not currently possible? It's not a deal breaker for us. Neil Thackeray Sr. Systems Engineer Beckman Institute for Advanced Science and Technology University of Illinois at Urbana-Champaign 405 N. 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I did a grep for btrfs on the logs and didn't see anything outside of the configs. Neil Thackeray Sr. Systems Engineer Beckman Institute for Advanced Science and Technology University of Illinois at Urbana-Champaign 405 N. 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You are right, the mkfs.btrfs call is missing. > Does disk_config support creating BTRFS file systems? BTRFS is supported by setup-storage (disk_config), but I'm not sure if on a LVM? Do you have mkfs.btrfs in the nfsroot? Check if this error is in the logs: BTRFS tools not found in PATH -- best regards Thomas
