From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34722) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z2hvA-0008I5-2c for qemu-devel@nongnu.org; Wed, 10 Jun 2015 11:28:04 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Z2hv5-0002y3-Rz for qemu-devel@nongnu.org; Wed, 10 Jun 2015 11:28:04 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49603) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z2hv5-0002xz-NQ for qemu-devel@nongnu.org; Wed, 10 Jun 2015 11:27:59 -0400 Date: Wed, 10 Jun 2015 16:27:56 +0100 From: Stefan Hajnoczi Message-ID: <20150610152756.GA17294@stefanha-thinkpad.redhat.com> References: <1433776886-27239-1-git-send-email-vsementsov@virtuozzo.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="6TrnltStXW4iwmi0" Content-Disposition: inline In-Reply-To: <1433776886-27239-1-git-send-email-vsementsov@virtuozzo.com> Subject: Re: [Qemu-devel] [PATCH v2 RFC 0/8] block: persistent dirty bitmaps List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Vladimir Sementsov-Ogievskiy Cc: kwolf@redhat.com, qemu-devel@nongnu.org, pbonzini@redhat.com, den@openvz.org, jsnow@redhat.com --6TrnltStXW4iwmi0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Jun 08, 2015 at 06:21:18PM +0300, Vladimir Sementsov-Ogievskiy wrot= e: > QCow2 header is extended by fields 'nb_dirty_bitmaps' and > 'dirty_bitmaps_offset' like with snapshots. >=20 > Proposed command line syntax is the following: >=20 > -dirty-bitmap [option1=3Dval1][,option2=3Dval2]... Two questions: 1. How does this code ensure that the dirty bitmap is consistent after crash/power failure? At the minimum, enabled dirty bitmaps must be discarded after crash/power failure if we cannot guarantee they are up-to-date. It's worse to rely on an outdated dirty bitmap than to detect failure and start afresh. 2. How do persistent dirty bitmaps work with live migration? Remember there are two storage cases for live migration: shared storage (NAS or SAN) and non-shared storage (disk images must be copied over). --6TrnltStXW4iwmi0 Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJVeFd8AAoJEJykq7OBq3PIMqUH/2AP4Y6CV3Bsl/6Lvbha3xuV 7+uo6x40T4Ytu9r7+uhZMAHxasGK88cxJlkQlozZmWqDQ72vaWiAsh6Iru1bVorm jRDYTkjvVBjJNZLkz5oYeBlLgKs6BVhLHIh1fFgQWM50uq8mmSWnz2qif07IdyUO GCfeNJe1pTm47fsJLY3Aan8M976fruhs8XP8TueoE1HGaozYdySZyOPOP9fEGt9M TCIxDVNpXwZRjMSTAQGjhHe034F1BNSYDxbSz6YhggTlwxJ9+yL+bD4gXJ9ecFhN 1nxXvI1CODd+abrwd64oYircEQ+bHUFVTuQE5PhQs8+nBL3nOKgVM3ZHRCxH9wM= =KYG2 -----END PGP SIGNATURE----- --6TrnltStXW4iwmi0--