I don't know where to write this up really, so let me try debian-user.
When I partioned my new netbook I left myself a reasonable amount of
space unpartitioned, in case I should ever want it. Well, of course,
then I wanted it. Specifically, I have: SSD nvme0n1 containing GPT
partitions; nvme0n1p6 is a LUKS volume containing my main LVM PV.
I didn't want to reboot. I thought that it should be possible to
achieve this. It was a bit of a palaver but I seem to have succeeded.
1. Discover that none of the "friendly" partition tools would work on
an in-use partition table.
2. Use sfdisk:
# sfdisk -d /dev/nvme0n1 >before
# cp before after
# emacs after &
This part could be quite fiddly. In my setup the free space
was right after the partition I wanted to resize - by design.
So all I had to do was change the right "size=" number.
If any of the "start=" needed changing, this would all be MUCH
harder. The numbers seem to be in 512-byte sectors.
Take a deep breath and:
# sfdisk /dev/nvme0n1 <after
Get an error message from sfdisk saying it refuses because the
partition table is in use, so:
# sfdisk --no-reread /dev/nvme0n1 <after
# partprobe
This worked: cat /proc/partitions showed that nvme0n1p6 was
now bigger.
3. Search the intertubes to try to figure out whether
`cryptsetup resize' was safe to use on a running LUKS device.
I found some suggestions that it was, from people who looked
like they had actually tried it.
I ran `dmsetup table --showkeys' just in case, as if I was
fast that might make it possible to put things back if it
went wrong.
So,
# cryptsetup resize nvme0n1p6_crypt
Another dmsetup table showed me that the 4k offset was still in
place and indeed only the size had changed - so it had worked.
4.
# pvresize /dev/mapper/nvme0n1p6_crypt
We're getting onto the home straight!
5.
Oh but I wanted to fill the new space full of random data first.
So I made and wiped a few LVs like this
# lvcreate -L 10G -n wipe1a vg-zealot2
# dd if=/dev/urandom of=/dev/vg-zealot2/wipe1a &
etc. The idea being that when I had wiped one I could lvremove
it and finally have some space, without having to wait for
the whole wipe to complete.
The final lvcreate to use up the remaining space was
# lvcreate -l <free PEs from vgdisplay> -n wipe2 vg-zealot2
I thought about maybe filing a bug against something, complaining that
this wasn't easier. gparted, maybe. If someone else still wants to
do that please X-Debbugs-CC me.
Ian.
--
Ian Jackson <ijack...@chiark.greenend.org.uk> These opinions are my own.
If I emailed you from an address @fyvzl.net or @evade.org.uk, that is
a private address which bypasses my fierce spamfilter.
