Re: [RFC Patch 00/25] COarse-grain LOck-stepping Virtual Machines for Non-stop Service

[Wen Congyang <ghostwcy@gmail.com>]

At 2014/7/18 22:18, Andrew Cooper Wrote:
> On 18/07/14 12:38, Wen Congyang wrote:
>> Virtual machine (VM) replication is a well known technique for providing
>> application-agnostic software-implemented hardware fault tolerance -
>> "non-stop service". Currently, remus provides this function, but it buffers
>> all output packets, and the latency is unacceptable.
>>
>> In xen summit 2012, We introduce a new VM replication solution: colo
>> (COarse-grain LOck-stepping virtual machine). The presentation is in
>> the following URL:
>> http://www.slideshare.net/xen_com_mgr/colo-coarsegrain-lockstepping-virtual-machines-for-nonstop-service
>>
>> Here is the summary of the solution:
>> >From the client's point of view, as long as the client observes identical
>> responses from the primary and secondary VMs, according to the service
>> semantics, then the secondary vm is a valid replica of the primary
>> vm, and can successfully take over when a hardware failure of the
>> primary vm is detected.
>>
>> This patchset is RFC, and implements the frame of colo:
>> 1. Both primary vm and secondary vm are running
>> 2. do checkoint
>>
>> This patchset is based on remus-v15, and use migration v1. Only supports hvm
>> guest now.
>>
>> TODO list:
>> 1. rebase to remus-v17 or newer
>> 2. support migration v2
>> 3. nic/disk replication
>> 4. support pvm
>
> This is an interesting set of patches.  One query I have is what you
> mean by "support migration v2".
>
> While I am developing migration v2, the old legacy code is left in place
> for easier testing and development purposes, but when the migration v2
> code does finally get committed, the legacy migration code will be
> deleted.
>
> The legacy code is unfit for purpose and entirely replaced by v2, in a
> backwards-compatible manor given the included conversion script (not
> that that matters for Remus/colo).


We use migration to implement remus/colo. If migration v2 is merged into 
upstream
xen, I think I need to add codes to migration v2, and make colo can work
with migration v2.

Thanks
Wen Congyang

>
> ~Andrew
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel
>