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Date: Sun, 21 Feb 2010 15:18:10 -0500
Message-ID: <6294c32a1002211218t25c774fft28e990bf9e2237f0@mail.gmail.com>
From: Selim Levy <sjtlevy@gmail.com>
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Subject: Re: [dm-crypt] configuration files
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To: dm-crypt@saout.de, Bryan Kadzban <bryan.kadzban@gmail.com>

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Hi Brian,

Thanks for your input.

On 21 February 2010 12:10, Bryan Kadzban <bryan.kadzban@gmail.com> wrote:

> Selim Levy wrote:
> > The contents of the rescue's /etc/crypttab, for which I've tried various
> > things is:
> > # cat crypttab
> > sdb3_crypt /dev/sdb3 none luks
>
> So, from 1000 miles away...
>

That's fine.  I'm even further away! ;)


> Doesn't Debian's initramfs bring up udev and let you use the
> /dev/disk/by-*/ symlinks in crypttab?  That's a *LOT* better way to find
> this drive (in your case, by-id might work, and by-uuid will almost
> definitely work, assuming a new-enough udev that can find the UUID of a
> LUKS volume).  Maybe poke around in /dev/disk when you're at the busybox
> prompt, and see what you can find.
> (If it doesn't bring up udev and let you use those symlinks, then ...
> why not?  :-P  Not a question for you obviously, but more for the Debian
> maintainers.)
>
> Anyway, then you don't care which sd* name is given to this device,
> since you're using an explicitly-guaranteed-stable name for it.
>

Hmmmm.... that's really interesting.  I played around at the busybox prompt
and took down all the info in the /dev/disk/by-* directories (which do get
created).  I redirected output of 'ls -alF' commands from those directories
to file and have the info available to me.

So here's what I've now confirmed:
When I boot into my main/internal hd, /dev/sda, sdb and sdc are the
following: internal hd, cardreader, external hd (respectively).
When I boot into my rescue/external system, they are the following: internal
hd, external hd, cardreader.

How do I go about using the /dev/disk/by-* devices with dm-crypt?  Does it
only require modifying, as before, /etc/fstab and /proc/cmdline?  Or is
there something else I should play around with?

I'm definitely getting closer!  Thanks for your help!

Cheers,
Selim

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Hi Brian,<br><br>Thanks for your input.<br><br><div class=3D"gmail_quote">O=
n 21 February 2010 12:10, Bryan Kadzban <span dir=3D"ltr">&lt;<a href=3D"ma=
ilto:bryan.kadzban@gmail.com" target=3D"_blank">bryan.kadzban@gmail.com</a>=
&gt;</span> wrote:<br>


<blockquote class=3D"gmail_quote" style=3D"border-left: 1px solid rgb(204, =
204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div>Selim Levy w=
rote:<br>
&gt; The contents of the rescue&#39;s /etc/crypttab, for which I&#39;ve tri=
ed various<br>
&gt; things is:<br>
&gt; # cat crypttab<br>
&gt; sdb3_crypt /dev/sdb3 none luks<br>
<br>
</div>So, from 1000 miles away...<br></blockquote><div><br>That&#39;s fine.=
=A0 I&#39;m even further away! ;)<br>=A0</div><blockquote class=3D"gmail_qu=
ote" style=3D"border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0p=
t 0.8ex; padding-left: 1ex;">



Doesn&#39;t Debian&#39;s initramfs bring up udev and let you use the<br>
/dev/disk/by-*/ symlinks in crypttab? =A0That&#39;s a *LOT* better way to f=
ind<br>
this drive (in your case, by-id might work, and by-uuid will almost<br>
definitely work, assuming a new-enough udev that can find the UUID of a<br>
LUKS volume). =A0Maybe poke around in /dev/disk when you&#39;re at the busy=
box<br>
prompt, and see what you can find.<br>
(If it doesn&#39;t bring up udev and let you use those symlinks, then ...<b=
r>
why not? =A0:-P =A0Not a question for you obviously, but more for the Debia=
n<br>
maintainers.)<br>
<br>
Anyway, then you don&#39;t care which sd* name is given to this device,<br>
since you&#39;re using an explicitly-guaranteed-stable name for it.<br>
</blockquote></div><br>Hmmmm.... that&#39;s really interesting.=A0 I played=
 around at the busybox
prompt and took down all the info in the /dev/disk/by-* directories
(which do get created).=A0 I redirected output of &#39;ls -alF&#39; command=
s from those directories to file and have the info available to me.<br>
<br>So here&#39;s what I&#39;ve now confirmed:<br>When I boot into my main/=
internal hd, /dev/sda, sdb and sdc are the following: internal hd, cardread=
er, external hd (respectively).<br>When I boot into my rescue/external syst=
em, they are the following: internal hd, external hd, cardreader.<br>
<br>How do I go about using the /dev/disk/by-* devices with dm-crypt?=A0 Do=
es it only require modifying, as before, /etc/fstab and /proc/cmdline?=A0 O=
r is there something else I should play around with?<br><br>I&#39;m definit=
ely getting closer!=A0 Thanks for your help!<br>
<br>Cheers,<br>Selim<br>

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