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From: Sreyan Chakravarty <sreyan32@gmail.com>
Date: Sat, 21 Nov 2020 08:40:44 +0530
Message-ID: <CAMaziXsY6vpQdD+QQzW_1Km+Ltf41tz0G1WG5xAUiMARFWHoyw@mail.gmail.com>
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Subject: [linux-lvm] What is the use of thin snapshots if the external
 origin cannot be set to writable ?
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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 snapshot if I can't change my
original volume ?

Is there some sort of resolution ?

-- 
Regards,
Sreyan Chakravarty

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<div dir=3D"ltr">I am looking into thin snapshots since the older COW snaps=
hots delay my boot enormously.<div><br></div><div>My normal root fs is on a=
 normal &quot;non-thin&quot; volume.=C2=A0</div><div><br></div><div>So to m=
ake a snapshot I have boot into a live cd environment then set my root fs v=
olume to read-only and then set it to inactive.</div><div><br></div><div>Co=
mmands:</div><div><br></div><div>=C2=A0 =C2=A0 =C2=A0 =C2=A0sudo lvchange -=
pr vgfedora/fedora</div><div>=C2=A0 =C2=A0 =C2=A0 =C2=A0sudo lvchange -an v=
gfedora/fedora</div><div><br></div><div>Now I create the thin snapshot usin=
g lvcreate, after that I need to restore my root LVS to its original state:=
</div><div><br></div><div>=C2=A0 =C2=A0 =C2=A0sudo lvchange -ay vgfedora/fe=
dora</div><div><br></div><div>=C2=A0 =C2=A0 =C2=A0 sudo lvchange -prw vgfed=
ora/fedora</div><div><br></div><div>This fails with:</div><div><br></div><d=
iv>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 Command on LV vgfedora/fedora =
uses options that are invalid with LV parameters: lv_is_external_origin.</d=
iv><div><br></div><div><br></div><div>I mean what is the point of creating =
a snapshot if I can&#39;t change my original volume ?</div><div><br></div><=
div>Is there some sort of resolution ?<br clear=3D"all"><div><br></div>-- <=
br><div dir=3D"ltr" class=3D"gmail_signature" data-smartmail=3D"gmail_signa=
ture"><div dir=3D"ltr">Regards,<div>Sreyan Chakravarty</div></div></div></d=
iv></div>

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