Resizing luks partition "in front"

Question

Hello
I have currently the following partitioning scheme:
.-(~)----------------------------------------------------------------------------------------------------(root@tirion)-
`--# fdisk -l /dev/sda
Disk /dev/sda: 107.1 GiB, 115033153536 bytes, 224674128 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
Disklabel type: dos
Disk identifier: 0x4488c4dc
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 63 192779 192717 94.1M 83 Linux
/dev/sda2 192780 224674127 224481348 107G 83 Linux
sda1 is a normal ext4 partition, sda2 LUKS with ext4
I found out, how I can grow a LUKS partition on the "end", but how can I get rid of sda1 and resize the luks partition to take all of the space?

Answer 1

Growing, or resizing in general, only happens on the end. So the way to do that would be to delete sda1 & sda2 (in the partition table that is) and create a new partition sda1 over the entire disk. Then you'd need to move the data from the old sda2 to be located where they outta be, so say for example your new partition would be like e.g.
Device Boot Start End Sectors Size Id Type
/dev/sda1 2048 224674127 224672080 107G 83 Linux
That would mean sda2 used to start at 192780*512=98703360 and the new one would now start at 2048*512=1048576 -- So I guess you could move data e.g. with dd:
dd bs=4M if=/dev/sda skip=98703360 iflag=skip_bytes of=/dev/sda seek=1048576 oflag=seek_bytes
It should put the data of the old sda2 right in the new sda1 location, so you can use it as expected. Then you can then grow your filesystem as usual (on the end) to take all the space/partition.
Assuming sda2 has a LUKS header, a simply way to make sure your at the right place would be:
dd if=/dev/sda bs=4 count=1 skip=98703360 iflag=skip_bytes
If it's right, it should read/show "LUKS"
Of course you should have a backup of your data before doing any of that. (Also some tools like maybe gparted or something might be able to do the whole thing "automatically" for you, I don't know.)