[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Qemu-devel] Re: Live migration protocol, device features, ABIs and ot

From: Anthony Liguori
Subject: [Qemu-devel] Re: Live migration protocol, device features, ABIs and other beasts
Date: Mon, 23 Nov 2009 09:05:58 -0600
User-agent: Thunderbird (X11/20090825)

Gleb Natapov wrote:
Then I don't see why Juan claims what he claims.

Live migration is unidirectional. As long as qemu can send out all of the data without the stream closing, it will "succeed" on the source. While this may sound like a bug, it's an impossible problem to solve as it's dealing with reliable communication between two unreliable nodes (i.e. the two general's problem). This is why the source qemu does not exit after a successful live migration. It merely stays in the stopped state. The idea is that a third party management tool can be the "reliable third party" that can make the final determination about whether the migration has succeeded and take actions on the source and destination nodes appropriately.

In this precise case, if post_load() fails, it may or may not cause the source to fail the migration depending on how large the TCP window sizes are, how much data is in flight, and how much state is left to process.


Anthony Liguori

reply via email to

[Prev in Thread] Current Thread [Next in Thread]