How use thin snapshots with a non-thin root filesystem ?

[Sreyan Chakravarty]

I am looking into thin snapshots since the older COW snapshots delay my
boot enormously.

My normal root fs is on a normal "non-thin" volume.

So to make a snapshot I have boot into a live cd environment then set my
root fs volume to read-only and then set it to inactive.

Commands:

sudo lvchange -pr vgfedora/fedora
       sudo lvchange -an vgfedora/fedora

Now I create the thin snapshot using lvcreate, after that I need to restore
my root LVS to its original state:

sudo lvchange -ay vgfedora/fedora

sudo lvchange -prw vgfedora/fedora

This fails with:

Command on LV vgfedora/fedora uses options that are invalid
with LV parameters: lv_is_external_origin.

I mean what is the point of creating a thin snapshot if I can't change my
original volume ?

What am I doing wrong?

[Samuel Sieb]

On 11/21/20 12:25 AM, Sreyan Chakravarty wrote:
> I am looking into thin snapshots since the older COW snapshots delay my 
> boot enormously.
>
> My normal root fs is on a normal "non-thin" volume.
>
> So to make a snapshot I have boot into a live cd environment then set my 
> root fs volume to read-only and then set it to inactive.
>
> I mean what is the point of creating a thin snapshot if I can't change 
> my original volume ?
>
> What am I doing wrong?

I'm pretty sure that you can only make a thin snaphot from a thin LV.

[Sreyan Chakravarty]

On Sat, Nov 21, 2020 at 2:00 PM Samuel Sieb  wrote:
> I'm pretty sure that you can only make a thin snaphot from a thin LV.

Can my non-thin LV be converted to a thin LV now ?

[Sreyan Chakravarty]

On Sat, Nov 21, 2020 at 2:00 PM Samuel Sieb  wrote:
> I'm pretty sure that you can only make a thin snaphot from a thin LV.

It seems I can convert:

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/htm...

[Sreyan Chakravarty]

On Sat, Nov 21, 2020 at 2:09 PM Sreyan Chakravarty 
wrote:
> It seems I can convert:
>
> https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/htm...

But unfortunately, this is a destructive convert. Any way I can preserve my
data after the convert ? Maybe something with Clonezilla ?