From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35707) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1f5XYK-0007ff-OS for Qemu-devel@nongnu.org; Mon, 09 Apr 2018 10:13:49 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1f5XYH-0006rZ-Ko for Qemu-devel@nongnu.org; Mon, 09 Apr 2018 10:13:48 -0400 References: <9b490d71-4f3e-9069-9c92-89d27e107f57@redhat.com> <20180409091146.GC5294@localhost.localdomain> From: Eric Blake Message-ID: <521f2f27-fd10-5745-ddfd-3cf1fff3013e@redhat.com> Date: Mon, 9 Apr 2018 09:13:42 -0500 MIME-Version: 1.0 In-Reply-To: <20180409091146.GC5294@localhost.localdomain> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="l3NHnmLYRiqNmIxIUV4tDOofc12tINbV3" Subject: Re: [Qemu-devel] [Qemu-block] block-stream/commit and mixing internal and external snapshots List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: "Qemu-devel@nongnu.org" , qemu block This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --l3NHnmLYRiqNmIxIUV4tDOofc12tINbV3 From: Eric Blake To: Kevin Wolf Cc: "Qemu-devel@nongnu.org" , qemu block Message-ID: <521f2f27-fd10-5745-ddfd-3cf1fff3013e@redhat.com> Subject: Re: [Qemu-block] block-stream/commit and mixing internal and external snapshots References: <9b490d71-4f3e-9069-9c92-89d27e107f57@redhat.com> <20180409091146.GC5294@localhost.localdomain> In-Reply-To: <20180409091146.GC5294@localhost.localdomain> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 04/09/2018 04:11 AM, Kevin Wolf wrote: > Am 07.04.2018 um 00:16 hat Eric Blake geschrieben: >> Perhaps others have already known this, but I just realized that if yo= u >> mix internal and external snapshots, you can set yourself up for massi= ve >> failures when trying to use block-stream or block-commit to consolidat= e >> data across the external backing chain, without also thinking about th= e >> internal snapshots. >=20 > Yeah, internal and external snapshots don't mix well. Basically, the > only thing that will work reliably is having a qcow2 image with interna= l > snapshots at the top, and then an immutable backing chain without > internal snapshots below it. I may try to tackle some safety valve additions in 2.13; but as the problem is pre-existing and not a late regression in 2.12, it is not a candidate for rushing anything into -rc3. --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org --l3NHnmLYRiqNmIxIUV4tDOofc12tINbV3 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEzBAEBCAAdFiEEccLMIrHEYCkn0vOqp6FrSiUnQ2oFAlrLdRYACgkQp6FrSiUn Q2oy0wf/b/Rv1LQHrNVa0CHBcEIUpqvWNDV8LpKMooJ80ZR9EJJsnuldvPqS7FTm cjeLFs4jyob8aUEumI+eLv0ipy5XdhkD9aoYiqhI5KkaOvmMpMgSA/GO1xFEMy1O ubky83F12mSGRBSqsJfz7QxQlit1uS9JCYEESydO1pGkwUvYq06640uVAWHQIepU F8UFfDie+jhjjEnB1PiEueh4DPSFYvlvEDslKLiuri73I2eOgNjpyt30O8wOEi75 QlIfntIT1c+3AHeTbfSdNprjecFlAaplXxEVJCKx4RvUtDnXUm1Cnx+Q25lLE3ER Ikf80F8zmRVQYNZlCDJMsxH6BR1YHw== =Oz51 -----END PGP SIGNATURE----- --l3NHnmLYRiqNmIxIUV4tDOofc12tINbV3--