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In general, kickstart has good support for installing onto btrfs
subvolumes. However, there is one case that has a small problem:
re-installing onto an existing subvol rootfs and/or /boot. To do an install, anaconda requires that the rootfs and /boot be "freshly formatted." For regular partitions and LVMlv, this presents no problem, just reformat the partition or LVMlv. On the other hand, a btrfs subvolume more closely resembles a directory than a partition and how do you re-format a directory? ... well, by deleting it and then re-defining it. I can easily do this when I do a regular gui install but kickstart is another matter. I proposed an update to anaconda/pykickstaert to add the "--reclaim" option for the btrfs command. This was rejected by anaconda developers because it did not fit with anaconda architecture (my words). An alternative was proposed to use clearpart to delete the subvolume by referring to the subvolume by it unique UUID. I do not find this useful because I cannot rerun a kickstart install without changing the kickstart file (each run will involve a different UUID). I do not want to carry my local modification so I came up with an alternative that requires no modification, works, and works if re-run without changing the kickstart file. Solution: I use a %pre section to delete the subvolume. Given a system with /boot on a ext4 partition and an existing btrfs volume supporting root6 and home subvolumes, it would look something like: ############### clearpart --none ... part swap --fstype=swap --noformat --_onpart_=UUID=a3b0c2ad-88c8-4d6d-876c-7c52881ab854 #part /boot --fstype=ext4 --_onpart_=sda4 #part /boot --fstype=ext4 --_onpart_=sda5 part /boot --fstype=ext4 --_onpart_=sda6 #part /boot --fstype=ext4 --_onpart_=sda7 part btrfs.10 --fstype=btrfs --noformat --label=ten --_onpart_=UUID=0f0f82cb-ed27-4468-a18c-64a877b64329 btrfs / --subvol --name=root6 ten btrfs /var --subvol --name=var6 ten btrfs /home --subvol --name=home --noformat ten ... %pre --log=/tmp/pre-install.log echo "manage the btrfs subvolumes" mkdir /mnt/btrfsvol mount UUID=0f0f82cb-ed27-4468-a18c-64a877b64329 /mnt/btrfsvol btrfs subvol list /mnt/btrfsvol btrfs subvol delete /mnt/btrfsvol/root6 btrfs subvol delete /mnt/btrfsvol/var6 btrfs subvol list /mnt/btrfsvol umount /mnt/btrfsvol rmdir /mnt/btrfsvol %end %post --nochroot --log=/mnt/sysimage/root/post-install.log cp -v /tmp/pre-install.log /mnt/sysimage/root %end ############# The first time this is run, the "btrfs subvol delete" will produce errors. Thereafter, reruns will delete the subvols so they can be re-installed. Note: Besides this mailing list, this might be good information to add to the kickstart documentation. Gene |
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