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From: | Anthony Liguori |
Subject: | Re: [Qemu-devel] [PATCH 3/4] Purge migration of (almost) everything to do with monitors |
Date: | Fri, 09 Mar 2012 12:53:44 -0600 |
User-agent: | Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.23) Gecko/20110922 Lightning/1.0b2 Thunderbird/3.1.15 |
On 03/09/2012 12:45 PM, Eric Blake wrote:
On 03/09/2012 11:31 AM, Anthony Liguori wrote:On 03/09/2012 12:20 PM, Jan Kiszka wrote:On 2012-03-09 19:13, Luiz Capitulino wrote:The Monitor object is passed back and forth within the migration/savevm code so that it can print errors and progress to the user. However, that approach assumes a HMP monitor, being completely invalid in QMP. This commit drops almost every single usage of the Monitor object, all monitor_printf() calls have been converted into DPRINTF() ones.I guess for most printfs, this is OK. But do you provide an alternative for the block migration progress output? I did not find anything on first glance. That is not a debugging feature.The block migration progress stuff is horribly broken and I regret ever merging it. Are you actively relying on this? Does block migration even work? Could we just remove block migration entirely...Libvirt has already exposed block migration to users,
:-( Do you rely on the progress stats that are printed?
but it is untested; if, as you say, it is horribly broken, then libvirt needs to pass on the error message back to the user that it is broken. But we regularly get people complaining that they don't have shared storage set up, and they are looking for a magic bullet that will do block migration alongside the domain migration; perhaps libvirt can still provide that with block mirroring or other (working) solutions from the same API it gives to the user if you end up pulling it out of the migrate QMP command.
Well block mirroring is hopefully around the corner. Regards, Anthony Liguori
At the end of the day, it's your call whether to pull it out, and libvirt will adapt, but it would be nice to know what kosher working alternative(s) to use instead.
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