/home partition or LVM logvol will be dropped and ignored after bootc install to-existing-root

[henrywang]

If the system has a dedicated /home partition or LVM logvol, this part of disk will be dropped/ignored after bootc install to-existing-root. This part of disk will not be used by bootc system.
For example:
This is the system df output before bootc install to-existing-root.

    Filesystem                                       Type      Size  Used Avail Use% Mounted on
    devtmpfs                                         devtmpfs  4.0M     0  4.0M   0% /dev
    tmpfs                                            tmpfs     251G     0  251G   0% /dev/shm
    tmpfs                                            tmpfs     101G   12M  101G   1% /run
    efivarfs                                         efivarfs  512K  6.7K  506K   2% /sys/firmware/efi/efivars
    /dev/mapper/cs_ampere--mtjade--altramax--01-root xfs        70G  2.5G   68G   4% /
    /dev/nvme0n1p2                                   xfs       960M  201M  760M  21% /boot
    /dev/nvme0n1p1                                   vfat      599M  7.0M  592M   2% /boot/efi
    /dev/mapper/cs_ampere--mtjade--altramax--01-home xfs       819G  5.8G  813G   1% /home
    tmpfs                                            tmpfs      51G     0   51G   0% /run/user/0
    tmpfs                                            tmpfs      51G  4.0K   51G   1% /run/user/1000

This is the system df output after bootc install. Almost 800G disk space will not be used.

    Filesystem                                       Type      Size  Used Avail Use% Mounted on
    devtmpfs                                         devtmpfs  4.0M     0  4.0M   0% /dev
    tmpfs                                            tmpfs     251G     0  251G   0% /dev/shm
    tmpfs                                            tmpfs     101G   12M  101G   1% /run
    efivarfs                                         efivarfs  512K  6.6K  506K   2% /sys/firmware/efi/efivars
    /dev/mapper/cs_ampere--mtjade--altramax--01-root xfs        70G  5.4G   65G   8% /sysroot
    overlay                                          overlay   7.3M  7.3M     0 100% /
    /dev/nvme0n1p2                                   xfs       960M   56M  905M   6% /boot
    tmpfs                                            tmpfs     251G   96K  251G   1% /tmp
    tmpfs                                            tmpfs      51G     0   51G   0% /run/user/1000

Disk partition info:

    Disk /dev/nvme0n1: 894.25 GiB, 960197124096 bytes, 1875385008 sectors
    Disk model: SAMSUNG MZ1LB960HAJQ-00007
    Units: sectors of 1 * 512 = 512 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Disklabel type: gpt
    Disk identifier: 6A257643-7710-49F0-A752-0FD78B25237E
  
    Device           Start        End    Sectors   Size Type
    /dev/nvme0n1p1    2048    1230847    1228800   600M EFI System
    /dev/nvme0n1p2 1230848    3327999    2097152     1G Linux filesystem
    /dev/nvme0n1p3 3328000 1875384319 1872056320 892.7G Linux LVM
  
  
    Disk /dev/mapper/cs_ampere--mtjade--altramax--01-root: 70 GiB, 75161927680 bytes, 146800640 sectors
    Units: sectors of 1 * 512 = 512 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
  
  
    Disk /dev/mapper/cs_ampere--mtjade--altramax--01-swap: 4 GiB, 4294967296 bytes, 8388608 sectors
    Units: sectors of 1 * 512 = 512 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
  
  
    Disk /dev/loop0: 7.29 MiB, 7643136 bytes, 1866 sectors
    Units: sectors of 1 * 4096 = 4096 bytes
    Sector size (logical/physical): 4096 bytes / 4096 bytes
    I/O size (minimum/optimal): 4096 bytes / 4096 bytes
  
  
    Disk /dev/zram0: 8 GiB, 8589934592 bytes, 2097152 sectors
    Units: sectors of 1 * 4096 = 4096 bytes
    Sector size (logical/physical): 4096 bytes / 4096 bytes
    I/O size (minimum/optimal): 4096 bytes / 4096 bytes
  
  
    Disk /dev/mapper/cs_ampere--mtjade--altramax--01-home: 818.66 GiB, 879033843712 bytes, 1716862976 sectors
    Units: sectors of 1 * 512 = 512 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes

[cgwalters]

This is currently expected...I wouldn't call it a bug. But, what exactly we take from the target root with install to-existing-root is clearly not very intuitive. Longer term we probably need to get to a state where we either inherit more (including things like ssh keys, etc.) or less (by always blowing away the root).

[henrywang]

Yeah, I agree it's not a bug but one of installation scenarios.
The autopart in kickstart will give /home a very big space of the disk. So I filed this scenario here.