Re: [gentoo-user] Encrypted hard drives on LVM and urgent power shutdowns.

[tastytea]

On 2022-09-11 20:56-0500 Dale <rdalek1967@×××××.com> wrote:

> Howdy,
>
> Last night we had some bad weather where I live and we ended up with
> some power problems.  Ironically they went out a few hours after the
> storm was gone.  Anyway.  I had all sorts of encrypted drives open.
> My usual drives inside my puter plus the large 14TB external backup
> drive that is still copying files over.  Glad my UPS held up while I
> closed all those drives and did a proper shutdown.  Doing all that
> tho, it made me think about if I wasn't here to do all that.  Being
> Linux, I'd suspect that upsmon would tell the puter to do a proper
> shutdown which includes unmounting the file system, closing the
> encrypted drives, like I do with cryptsetup close <name> etc and then
> shutting down.  However, one has to ask, is it set up to do so by
> default?  I manage the encrypted drives manually.  I don't use the
> crypt services for that like people do when all of the system
> drive(s) is encrypted or when just /home is encrypted.  My encrypted
> stuff is mounted within /home or for the external backups, in /mnt.
> Thing is, some aren't open unless I'm using them or are external.
> Since I do it manually, is there a tool that sees they need
> unmounting and closing and does it or do I need to do something to
> make sure it is done before a shutdown? 
>
> I suspect this would happen on its own but I'd like to make sure.  I'd
> hate to mess up the file system badly on any of my drives or in a
> worst case scenario, brick a hard drive with some 1 in a million
> chance problem.
>
> I thought about having a drive connected, open and mounted that I
> don't really need and just do a shutdown, see what happens.  Then
> again, why not ask and see if anyone else has had this happen and if
> things turned out OK or if there was problems.  I'm lucky, most of
> the time I'm either home or very close by.  Still, it can happen when
> I'm not here.  I already wonder if upsmon will kick in correctly and
> do a proper shutdown.  After all, it has never had to before.  I'm
> running on faith that it will.  I hope I'm right. 
>
> Thoughts?  Default will take care of things?  I need to take steps to
> be sure in case I'm not here?  Personal experience?  A good theory?
> ;-)

Yes, /etc/init.d/mount-ro will take care of that. It first calls `sync`
and then calls `umount -r` on everything. It's set up to ruin on
shutdown by default. I'm sure systemd does something similar.

I don't think `cryptsetup luksClose` is necessary on shutdown, since it
only sets up the mapping(?).

Kind regards, tastytea