Re: [gentoo-user] Replace 8TB drive with 10TB drive on encrypted LVM

[Dale <rdalek1967@gmail.com>]

Rich Freeman wrote:
> On Wed, Sep 14, 2022 at 1:40 AM Dale <rdalek1967@gmail.com> wrote:
>> Now to replace my /home drive which is also close to full.  It's not
>> encrypted tho. The biggest difference in this and plain LVM, resizing
>> with cryptsetup or close and reopen.  Keep in mind, while I did all
>> this, LUKS, cryptsetup, whatever was open.  I'm not sure about this
>> being done while closed.  I did find one mention that it had to be open
>> at certain points.
>>
> If you want to do operations on a DM volume, then it needs to exist,
> which in the cryptsetup world means "open."
>
> Most of the details of how to do an operation like moving around
> encrypted volumes depends on the layers you're using (LUKS, LVM,
> mdadm, whatever), and how they're stacked.  If you're running LVM on
> top of LUKS then you create new LUKS volumes and add them to LVM and
> move stuff around.  If you're running LUKS on top of LVM then you add
> unencrypted volumes to LVM, extend the LV underlying LUKS, and then
> resize the LUKS volume.  Last comes resizing whatever filesystems are
> on top if desired.
>
> When you want to get advice around these kinds of operations it is
> usually necessary to detail exactly how things are set up, because to
> Linux they're just layers and you can stack them however you want.  A
> script that adds a hard drive to your setup will look different if
> you're running mdadm on the bottom vs LUKS vs LVM and so on.
>
> Plus if you do things in the wrong order there is actually a chance
> that it will work and leave you with half your filesystem on an
> encrypted drive and half of it on an unencrypted one, or whatever.  DM
> doesn't care - it just shuffles around blocks and transforms them as
> told, and as long as you stack things up the same way every time it
> should still work.  It just won't necessarily be doing what you want
> it to...
>


I see the point but wasn't aware there was more than one way to do it
with cryptsetup.  It seems there is several options for this.  I was
pretty sure LVM was on bottom and mentioned it in my original post. 
After reading your post, I got to wondering, did I do this the right
way?  So, I started looking to see how to tell for sure.  I used several
LVM type commands but didn't see anything that I recognized anyway. 
Keep in mind, I'm not real sure what I'm looking for either. Then I ran
lsblk -f and found a clue that I've never noticed before. 


sdd                                                                                                    

└─sdd1              LVM2_member LVM2 001         
pVnP2i-sj48-3co9-nJpa-9tQr-08pa-9JqASR               
  └─crypt-crypt     crypto_LUKS 2                
6e884aae-9377-49ef-a602-e13cba89a377                 
    └─crypt         ext4        1.0      crypt   
76653316-329f-4747-8fed-fc9b1723bd14      3.5T    79%
/home/dale/Desktop/Crypt


I know that is going to be line wrapped and mess up things but the part
I noticed was the drive partition "sdd1" and "LVM2 member".  On top of
that is crypto.  So, LVM is on bottom.  If that is the case, my pvmove
command should be moving what I think you call "raw data", doesn't
matter if it is encrypted or not, right?  Either way, other than
resizing the files system, I was dealing with LVM layers.  Just in case
it matters, could I have done everything but the file system resize
while it was closed?  It seems it is basically encrypted on the layer
just below the file system to me. 

Your post helped me to have a better idea of what I got here.  By all
means, point out if I got anything wrong.  Biggest thing, it seems to
have worked.  Still, I need more drive space.  :/

Thanks.

Dale

:-)  :-)