Dne 25. 09. 23 v 0:09 Jean-Marc Saffroy napsal(a):
Hello LVM experts,
I am trying to create a volume with the following properties:
- the volume can be resized
- the volume is encrypted
- the volume can be snapshotted (for online backups)
So I thought I'd create the volume with LVM, encrypt it with LUKS, and
snapshot it with LVM. However, LVM doesn't want to snapshot the unencrypted
LUKS volume, as it is not an actual logical volume known to LVM (and I am not
keen on snapshotting the encrypted volume, as that means the backup process
would need the passphrase to mount the encrypted snapshot).
Is there a good way to achieve this with LUKS and LVM, or should I look
elsewhere?
I have two ideas but I don't know if they are safe or practical:
- I could try running LVM (snapshots) ontop of LUKS (encryption)itself ontop
of LVM (resize)
Hi
Yep typical usage is to encrypt underlying PV - and then create LVs and its
snapshots on encrypted device.
- or I could try working with dmsetup to fill the gap between LUKS and LVM
I did simple tests with dmsetup, and that *seems* to work, however I am not
sure at all if that would be robust. An outline of my test:
- create an LVM volume (lvcreate) from a larger volume group
- make it a LUKS volume (cryptsetup lukfsFormat)
- "open" the LUKS volume (cryptsetup open)
- create a snapshot-origin volume from the open LUKS volume (dmsetup create)
- mount that as my active volume
- every time I want to do a backup:
create a temporary snapshot volume from the origin, mount it, run the
backup, unmount it, delete it
Usually those 'into encryption' want to have encrypted everything - thus even
layout of the whole storage.
Encrypting 'individual' LVs - while certainly 'doable' would i.e. create a
considerable larger amount of volumes that would need individual 'unlocking'
with each activation.
Speaking about snapshots - you should consider switching to 'thin-pools' for
far better performance...
Regards
Zdenek
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