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Wed, 13 Apr 2022 11:00:59 -0400 (EDT) Date: Wed, 13 Apr 2022 11:00:53 -0400 From: Demi Marie Obenour To: Zdenek Kabelac , dm-devel@redhat.com Message-ID: References: <6a6c09ad-73c9-2450-f1fb-0e3e4ba438e6@redhat.com> <20220412142905.GA26912@redhat.com> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.85 on 10.11.54.9 X-Mailman-Approved-At: Thu, 14 Apr 2022 11:17:24 +0000 Subject: Re: [dm-devel] Potential enhancements to dm-thin v2 X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: multipart/mixed; boundary="===============3645198189452590683==" Errors-To: dm-devel-bounces@redhat.com Sender: "dm-devel" X-Scanned-By: MIMEDefang 2.85 on 10.11.54.8 --===============3645198189452590683== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="1v7FTPIZIIn90/Gr" Content-Disposition: inline --1v7FTPIZIIn90/Gr Content-Type: text/plain; protected-headers=v1; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Date: Wed, 13 Apr 2022 11:00:53 -0400 From: Demi Marie Obenour To: Zdenek Kabelac , dm-devel@redhat.com Subject: Re: Potential enhancements to dm-thin v2 On Wed, Apr 13, 2022 at 09:55:00AM +0200, Zdenek Kabelac wrote: > Dne 12. 04. 22 v 16:29 David Teigland napsal(a): > > Dne 11. 04. 22 v 0:03 Demi Marie Obenour napsal(a): > > > For quite a while, I have wanted to write a tool to manage thin volum= es > > > that is not based on LVM. > >=20 > > On Tue, Apr 12, 2022 at 11:32:09AM +0200, Zdenek Kabelac wrote: > > > Here is actually the fundamental problem with your proposal - our des= ign was > > > about careful split between user-space and kernel 'who is the owner/h= older > > > of information'=C2=A0 - your proposal unfortunately does not fit the = model where > > > lvm2 is the authoritative owner of info about devices > >=20 > > The proposal is a new tool to manage dm-thin devices, not to rewrite lv= m. > > I would hope the tool is nothing at all like lvm, but rather "thinsetup" > > in the tradition of dmsetup, cryptsetup. I think it's a great idea and > > have wanted such a tool for years. I have a feeling that many have > > already written ad hoc thinsetup-like tools, and there would be fairly > > broad interest in it (especially if it has a proper lib api.) > >=20 >=20 >=20 > The problem with these 'ad-hoc' tools is their 'support - aka how to proc= eed > in case of any failure. >=20 > So while there will be no problem to generate many device in very fast wa= y - > the recoverability from failure will then be always individual based on t= he > surrounding environment. That=E2=80=99s why I want to stick a name and UUID in each thin device=E2= =80=99s metadata. That makes creating a thin device and associating it with a name an atomic operation, and means that if there is a failure, the sysadmin or management toolstack knows what it needs to do to clean up. --=20 Sincerely, Demi Marie Obenour (she/her/hers) Invisible Things Lab --1v7FTPIZIIn90/Gr Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEdodNnxM2uiJZBxxxsoi1X/+cIsEFAmJW5agACgkQsoi1X/+c IsGr6BAA3vBsGMqT3sSdL8jQZf0FQdvUofXFlwwuOnVNKq1qTHV/cUTKfw082R1t Bu5w4hgEZT8YXviQgSBSTGvnWlP+j6sIaUU/tjZeJVbK5vgFH/esrNGGlG1K8HwI sYXvH1uSxfLwwTpf1kV+gJ9YIc8zedhtHeKqLtb3WESnsD5JzulvqKOfb3mSIu5q +YH3F+L+gCDLjYMqV8nA4LJlePO0qx7tV6iKqzq+DdtQ/+I+pE1aRBQLn29ZXfS7 aOl+0lDccJ6i6/St8rY3OufA4m9zN6a7VxeN9o9FJ4Ato9M9p4LONTa1IfCD9xZr 2hr4lBNfsNWnBN4d9XeCQvI+5lch2Ny/oMDPPuHNfL4f1KZzfz0hXAyJJbdvm2Kh jib3w9viXbDWanVSW48cMMMxRZb7ODx8bG02RvnyHoNt0b6oP5R7ZKY9dAfxmNXG Q1PpqpObXZ1UBIFGk0uzxhCDHyqWm3q3l99pHpYZRPDtGoqu6zLFRMAeJEzS4I86 aGSX930hzVwuBevXaI0GEqh7l55s0qkxarEnlSdOp5IX1ZZNOnr3XTQnvZTUv9c6 YLoJz2O0EMNWSeIo4EH4qCUROhjXpmFEVGGDmclMpQSu9L6NKqaSznlyN20r10J3 5NYuxum5eepDX5h/Z3+R7d0XwkcXBrgj7LGkthD2TwgoOr9d9qU= =sTNg -----END PGP SIGNATURE----- --1v7FTPIZIIn90/Gr-- --===============3645198189452590683== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel --===============3645198189452590683==--