From mboxrd@z Thu Jan 1 00:00:00 1970 From: g.danti@assyoma.it Subject: Re: KVM in HA active/active + fault-tolerant configuration Date: Thu, 22 Aug 2013 08:59:18 +0200 Message-ID: References: <39187c68-9c18-4a42-bbb6-8704bf3f48a9@theiggy.com> <5aa7342b9d8de1d59e048b086d4fd6a9@assyoma.it> <5ab9e4b6-075b-4185-b935-06314f6b800f@theiggy.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Brian Jackson , To: Timon Wang Return-path: Received: from santino.mail.tiscali.it ([213.205.33.245]:52865 "EHLO santino.mail.tiscali.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753757Ab3HVG7X (ORCPT ); Thu, 22 Aug 2013 02:59:23 -0400 In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On 2013-08-22 02:35, Timon Wang wrote: > On Thu, Aug 22, 2013 at 5:47 AM, Brian Jackson > wrote: >> On Wednesday, August 21, 2013 3:49:09 PM CDT, g.danti@assyoma.it >> wrote: >>> >>> On 2013-08-21 21:40, Brian Jackson wrote: >>>> >>>> On Wednesday, August 21, 2013 6:02:31 AM CDT, g.danti@assyoma.it >>>> wrote: >>>> ... >>> >>> >>> Hi Brian, >>> thank you for your reply. >>> >>> As I googled extensively without finding anything, I was prepared to >>> a >>> similar response. >>> >>> Anyway, from what I understand, Qemu already use a similar approach >>> (tracking dirty memory pages) when live migrating virtual machines >>> to >>> another host. >>> >>> So what is missing is the "glue code" between Qemu and KVM/libvirt >>> stack, >>> right? >> >> >> Live migration isn't what you asked about (at least not from what I >> understood). Live migration is just moving a VM from one host to >> another. >> That is definitely supported by libvirt. Having a constantly running >> lock-step sync of guest state is what Qemu/KVM does not support. So >> with >> Qemu's current live migration abilities, if HostA dies, all it's >> guests will >> have downtime while they are restarted on other hosts. >> >> > > Live migration is not proper for support VM HA, when host went wrong, > these VMs on the host must be restart on another host based on the > same storage. > > I have googled for KVM FT for a while, but only find a project called > Kemari which was no longer updated. > I read some article about KVM FT, which said KVM may be support it in > future. > > Yes, I understand that live migration is not proper to VM HA/FT, but the basic working principles (track and copy dirty pages) is already at work in live migration. I was thinking to something along what Zheng suggested ("hot backup" with very frequent/continuous memory synchronization from a "master" guest). I totally overlooked Kemari, glad to see that someone point me to it. Shame that is dead (at the moment). Thanks you all guys. >>> >>> Thanks again. >>> >>>> ... >>> >>> -- >>> To unsubscribe from this list: send the line "unsubscribe kvm" in >>> the body of a message to majordomo@vger.kernelorg >>> >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>> >>> >> >> -- >> To unsubscribe from this list: send the line "unsubscribe kvm" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html