From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42696) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VantG-0003EO-Dw for qemu-devel@nongnu.org; Mon, 28 Oct 2013 10:34:03 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VantB-0002vs-Bc for qemu-devel@nongnu.org; Mon, 28 Oct 2013 10:33:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49154) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VantB-0002vi-3P for qemu-devel@nongnu.org; Mon, 28 Oct 2013 10:33:53 -0400 Message-ID: <526E75C6.1020307@redhat.com> Date: Mon, 28 Oct 2013 08:33:42 -0600 From: Eric Blake MIME-Version: 1.0 References: <5266F7C4.6080700@redhat.com> <526B41D0.90506@redhat.com> In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="uP6Rwak8liL9rRHXSl6h4GtgjJwBH27ir" Subject: Re: [Qemu-devel] About VM fork in QEMU List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Xinyang Ge Cc: Hayawardh Vijayakumar , qemu-devel@nongnu.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --uP6Rwak8liL9rRHXSl6h4GtgjJwBH27ir Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 10/26/2013 11:37 AM, Xinyang Ge wrote: >> External snapshots (via the blockdev-snapshot-sync QMP command) can be= >> taken in a matter of milliseconds if you only care about disk state. >> Furthermore, if you want to take a snapshot of both memory and disk >> state, such that the clone can be resumed from the same time, you can = do >> that with a guest downtime that only lasts as long as the >> blockdev-snapshot-sync, by first doing a migrate to file then doing th= e >> disk snapshot when the VM pauses at the end of migration. Resuming th= e >> original guest is fast; resuming from the migration file is a bit >> longer, but it is still the fastest way possible to resume from a >> memory+disk snapshot. If you need anything faster, then yes, you woul= d >> have to write patches to qemu to attempt cloning via fork() that makes= >> sure to modify the active disk in use by the fork child so as not to >> interfere with the fork parent. >=20 > I think migrating memory to file then doing external disk snapshot is > exactly what we want. Since we are using libvirt to manage different > VMs, could you give us some specific guides (or references) that how > we could migrate memory state to file using virsh interfaces and do > external snapshots? virsh snapshot-create-as $dom $name --live --memspec /path/to/memoryfile Libvirt usage questions might be better directed to the libvirt lists. --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org --uP6Rwak8liL9rRHXSl6h4GtgjJwBH27ir Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.15 (GNU/Linux) Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBCAAGBQJSbnXGAAoJEKeha0olJ0Nq6vQH/12qhCK8Gje7KuywliVp8Yr6 9LZwKvGfc7VZp5Xyvj/bJyMGg+JOgfg70Lk5ADLwQr+ju7awSn1xPc/YwbnZExVd gAN2p1sNkhuTkZWjxfgSj2bsbV2L8V0ZxEVtkCfZdw9EbmYtaNpSIvpFIFBlBwQp ZpmyUsGKm3a/TWm5gCA7AJKZU5iRZj2a83RKiF2gi+crHq6WV8Jy+OHvj5BmFGhb ZbuxC5vAllvQrQzVw2Ym8ojBoDcuHKCKsMwhhbSNyoEGDEBBSxLzAEiLG69gpYAE XdmnLiIql7XwSAJuDqZU/dQ8YvHVH4AMcZkwlMSIgVuS74XFB51jSb1DYcflcKs= =y/UT -----END PGP SIGNATURE----- --uP6Rwak8liL9rRHXSl6h4GtgjJwBH27ir--