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

[Dale]

tastytea wrote:
> 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
>
>


Thanks much for this info.  I figured there was some tool that would do
that regardless of what it was.  I know regular file systems would be
and couldn't imagine that encrypted would be any different but I didn't
want to find out I was wrong the hard way.  After all, this 14TB backup
has been running for a few days now. Even when it gets through, I have
to run it again because of additions and other changes I made in the
past few days.  While I could just start over with a fresh backup if it
got damaged, it would be time consuming to do so.  Also, it would put
data at risk if I had a failure of the running drives while that backup
was not available.  Not likely but bad things happen. 

Next time power fails, I'll just stop all the processes I can and then
do a shutdown, knowing that everything will close safely.  That will
save me some battery time as well. 

Thanks much. 

Dale

:-)  :-)