[arch-general] LUKS on LVM example in wiki

[Fons Adriaensen]

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

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It's also a pipe-dream, founded on self-delusion, nerd hubris
and hysterically inflated market opportunities. (Cory Doctorow)