From: Arno Wagner <arno@wagner.name>
To: dm-crypt@saout.de
Subject: Re: [dm-crypt] concurrency
Date: Sat, 26 Mar 2016 21:06:10 +0100 [thread overview]
Message-ID: <20160326200610.GA6499@tansi.org> (raw)
In-Reply-To: <56F6A1A2.4050805@dodo.com.au>
Hi,
in order to have a shared filesystem work, you need, well,
a shared filesystem! Do not under any circumstances share
the block-device or the LUKS-remapped decrypted block
device. I suspect you do soemthing like that, because
otherwise the question would not even arise.
The rigth way to do this is
raw-block-device -> LUKS decrypted block device -> Filesystem
-> export of that filesystem, e.g. via NFS.
(last two steps possibly one with other network filesystyems)
Of course, NFS (or the network filesystem of your choice)
has some transactional assurances and is missing others.
For example, on NFS, nothing is atomic, except locks
or rename operation (as far as I remember).
But if you do follow the right layering, what you have is
not a LUKS problem at all, but something stemming from the
filesystem layer and possibly wrong assumptions about the
assurances it offers.
Regards,
Arno
On Sat, Mar 26, 2016 at 15:50:10 CET, Hugh Bragg wrote:
> Should I be able to use Luks concurrently on a shared filesystem from
> different computers?
> Attempts so far have failed with writes not being seen from the other
> computer until both computers remount the filesystem or reboot.
> Specifically, virtualbox shareable disks and shared folders, but
> potentially, any nfs/cloud storage.
>
> Am I missing something or is there another tool for this case?
> _______________________________________________
> dm-crypt mailing list
> dm-crypt@saout.de
> http://www.saout.de/mailman/listinfo/dm-crypt
--
Arno Wagner, Dr. sc. techn., Dipl. Inform., Email: arno@wagner.name
GnuPG: ID: CB5D9718 FP: 12D6 C03B 1B30 33BB 13CF B774 E35C 5FA1 CB5D 9718
----
A good decision is based on knowledge and not on numbers. -- Plato
If it's in the news, don't worry about it. The very definition of
"news" is "something that hardly ever happens." -- Bruce Schneier
next prev parent reply other threads:[~2016-03-26 20:06 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-26 14:50 [dm-crypt] concurrency Hugh Bragg
2016-03-26 20:06 ` Arno Wagner [this message]
2016-03-27 0:53 ` Hugh Bragg
2016-03-27 4:33 ` Arno Wagner
2016-03-27 8:31 ` Hugh Bragg
2016-03-27 15:49 ` Arno Wagner
2016-03-27 16:30 ` Hugh Bragg
2016-03-27 7:51 ` Milan Broz
2016-03-27 16:52 ` Michael Kjörling
2016-03-27 17:56 ` Hugh Bragg
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160326200610.GA6499@tansi.org \
--to=arno@wagner.name \
--cc=dm-crypt@saout.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox