Re: BTRFS, LVM, LUKS

[Giovanni Biscuolo <g@xelera.eu>]

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Hello Alexandre,

wellcome to Guix!

Alexandre Oliva <lxoliva@fsfla.org> writes:

[...]

> My first concern is that it's not clear to me what's meant by lack of
> LVM support.  I saw patches around April-May 2015, some later
> discussions, but not much that would give me much of a clue as to what's
> really missing,

Guix is "just" not able to activate/assemble LVM volumes at boot, as a
consequence LVM volumes creation and activation is also missing in the
installer

[...]

> lvm, that lvm and device-mapper packages are missing altogether, or that
> device-mapper infrastructure is disabled in the kernel?

Device mapper is definitely supported
https://www.gnu.org/software/guix/manual/en/html_node/Mapped-Devices.html#Mapped-Devices
it's used for LUKS and mdraid (missing LVM)

> Full-disk encryption (LUKS) is also a strict requirement for me, and so
> is multi-disk BTRFS.

They are working, several of us tested them or are using them in
prodution; I personally manage a physical machine using multi-disk BTRFS
and tested root on BTRFS on LUKS a couple of times on a physical machine

> I'm willing and somewhat available to volunteer time and effort to
> contribute support for these, but I could use some mentoring in getting
> started and on track towards improving what needs to be improved in ways
> that are likely to be generally acceptable.

I cannot mentor, all I can say is that we (I'm also interested in LVM
support for some **legacy** system I manage [1]) must first undestand
how device-mapped device are activated and add support to for LVM ones

In this past discussion Ludovic states:
"It sounds like we’re almost there, I guess."
https://lists.gnu.org/archive/html/guix-devel/2015-05/msg00041.html
but that discussion did not lead to a patch request, nor a wip branch on
guix

As you can see there are no patches for LVM device-mapping
https://debbugs.gnu.org/cgi/pkgreport.cgi?package=guix-patches;archive=both;include=subject%3ALVM

I'm interested in contributing on this but currently I'm just able to
rewiev, test and/or coordinate development :-S

> I have not used GuixSD yet, to a large extent due to the stated lack of
> LVM support.

Please do not be blocked by the lack of LVM support, try start using
Guix on BTRFS on a physical host if you can

> I haven't got myself into Guix either *blush*, but maybe I
> could get started with it.  I suppose VMs might be a way to get started,
> but...  the machines I use are not very powerful, as in, laptops old
> enough as to support LibreBoot, so I haven't used virtualization much
> myself.

All I can say is that to start hacking (that means locally build several
packages or services) on Guix you need enough memory (at least 4GB but
8GB is far better... and use swap!) and enough CPU power (4 cores at
least); if you do not have a powerful host, a VM is suitable just for
testing Guix usage IMHO

[...]

HTH! Gio'.

[1] all new ones _must_ use BTRFS :-)

-- 
Giovanni Biscuolo

Xelera IT Infrastructures

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