LUKS on LVM example in wiki

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LUKS on LVM example in wiki

Fons Adriaensen-2
I've been reading the section 'LUKS on LVM' in the wiki page

<https://wiki.archlinux.org/index.php/Dm-crypt/Encrypting_an_entire_system>

and there's something I fail to understand.

Under 'Preparing the logical volumes', there is:

# lvcreate -L 500M -n tmp MyVol

(which isn't shown in the ascii picture just above).

Later, under 'Configuring fstab and crypttab' a tmpfs is created on the
encrypted /tmp partition:

dev/mapper/tmp         /tmp    tmpfs           defaults        0       0

Question: as far as I've understood, a tmpfs resides in RAM, with
overflow to /swap. So why is there a logical volume for /tmp ?
Or put otherwise, if /tmp is to reside on disk, why use a tmpfs ?

TIA,

--
FA

A world of exhaustive, reliable metadata would be an utopia.
It's also a pipe-dream, founded on self-delusion, nerd hubris
and hysterically inflated market opportunities. (Cory Doctorow)
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Re: LUKS on LVM example in wiki

Brett M. Gilio
Hello FA,

Did you get an answer to your question? Let me know if you still need help.

BMG

Brett M. Gilio
B.S. Biological Sciences
B.M. Music Composition
http://www.brettgilio.com/

"Sometimes the obvious is the enemy of the true."
- G. Stolzenberg

On 11/19/2017 09:53 AM, Fons Adriaensen wrote:

> I've been reading the section 'LUKS on LVM' in the wiki page
>
> <https://wiki.archlinux.org/index.php/Dm-crypt/Encrypting_an_entire_system>
>
> and there's something I fail to understand.
>
> Under 'Preparing the logical volumes', there is:
>
> # lvcreate -L 500M -n tmp MyVol
>
> (which isn't shown in the ascii picture just above).
>
> Later, under 'Configuring fstab and crypttab' a tmpfs is created on the
> encrypted /tmp partition:
>
> dev/mapper/tmp         /tmp    tmpfs           defaults        0       0
>
> Question: as far as I've understood, a tmpfs resides in RAM, with
> overflow to /swap. So why is there a logical volume for /tmp ?
> Or put otherwise, if /tmp is to reside on disk, why use a tmpfs ?
>
> TIA,
>