Re: [gentoo-user] LVM and moving things around

[Wol]

On 27/03/2022 20:17, Dale wrote:
> Howdy,
>
> I sort of started this on another thread but wanted to nail a few things
> down first.  I'm wanting to encrypt some parts of my data on /home.
> This is what I got hard drive wise.
>
>
> root@fireball / # pvs
>    PV         VG     Fmt  Attr PSize    PFree
>    /dev/sda7  OS     lvm2 a--  <124.46g 21.39g
>    /dev/sdb1  Home2  lvm2 a--    <5.46t     0
>    /dev/sdc1  Home2  lvm2 a--    <7.28t     0
>    /dev/sdd1  Home2  lvm2 a--    <7.28t     0
>    /dev/sde1  backup lvm2 a--   698.63g     0
> root@fireball / #
>
One big piece of missing information. What does fdisk say about 
sd[b,c,d]1? And can you add sdf1?

I'm guessing you've got three 8TB drives? Or is it two 8s and a 6? Can 
you get a third 8TB? And if you're encrypting *parts* of /home ... what 
parts?
>
> I've done some checking on sizes of things I want to encrypt and am
> weighing options.  I use LVM which should help make things easier.  I've
> downloaded and printed some howtos regarding shrinking the file system
> and LVM thingys.  It seems I need to shrink the file system while my
> /home partition is unmounted.  Then move the data off whichever drive I
> want to remove and then remove the drive itself.  After that I can
> encrypt the just removed drive and start moving files over, using rsync
> is my plan.  I think that is the basic steps.

Not necessarily.
>
> My question now comes to this.  When I encrypt one of the drives, can I
> then expand that drive with it being encrypted or is that not a option?
> I plan to encrypt two of the drives as one volume group and leave one
> other volume group as normal.  I just want to be sure whether or not I
> can expand a encrypted LVM drive the same as a normal LVM since both
> uses LVM.  I use cryptsetup commands to accomplish the encryption if
> that matters.  So as a example, I start with one 7TB drive encrypted,
> move some data to it, then want to add either the 5TB or 7TB drive.  Can
> I just expand it like a normal LVM or does it being encrypted change
> things?
>
> Thoughts?  My remove steps look sensible?  Expanding encrypted LVM
> possible?

If you are using LVM to do the encryption, then I can't see any problems 
adding a new PV to an encrypted VG.
>
> Dale
>
Personally, I'd use dm-crypt to encrypt the drive, and then the whole 
lot is encrypted, and put plain LVM over that. I've got dedicated layers 
for everything.

It looks like your home2 is 6TB+8TB+8TB. I'd get a new 8TB, put dm-crypt 
on it, and add it. Now I can remove the first 8TB, dm-crypt it and 
re-add it. Same with the second 8TB. Now remove the 6TB and there you 
are ...

My layout's rather different from yours, so I don't think I ought to say 
too much :-)

Cheers,
Wol