network buffering in fault tolerance

network buffering in fault tolerance

[Shivam Mehra]

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I came across this documentation with source code for providing network
buffering to applications
https://www.nfradead.org/~tgr/libnl/doc/api/route_2qdisc_2plug_8c_source.html
<https://www.infradead.org/~tgr/libnl/doc/api/route_2qdisc_2plug_8c_source.html>.
This network-buffering helps output-commit problem when providing fault
tolerance to virtual machines. The output is buffered until an
acknowledgement arrives from the backup VM and then released to the
external world. So that backup and primary VMs seem consistent externally.
Initially developed for XEN VMM to provide fault tolerance to VMs and I
think it's now available for QEMU too.

Where does the script reside which does network-buffering for checkpoints?
and what are the commands to make this happen?

I want to do this network-buffering for packets originating from an
application. Is it possible to do it in the same way as above? Does it do
any damage to the host kernel? Can I get  a simple working example for this?

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Re: network buffering in fault tolerance

[Jason Wang]

On 2020/9/30 下午1:12, Shivam Mehra wrote:
>
> I came across this documentation with source code for providing 
> network buffering to applications 
> https://www.nfradead.org/~tgr/libnl/doc/api/route_2qdisc_2plug_8c_source.html 
> <https://www.infradead.org/~tgr/libnl/doc/api/route_2qdisc_2plug_8c_source.html>. 
> This network-buffering helps output-commit problem when providing 
> fault tolerance to virtual machines. The output is buffered until an 
> acknowledgement arrives from the backup VM and then released to the 
> external world. So that backup and primary VMs seem consistent 
> externally. Initially developed for XEN VMM to provide fault tolerance 
> to VMs and I think it's now available for |QEMU| too.
>
> Where does the script reside which does network-buffering for 
> checkpoints? and what are the commands to make this happen?
>
> I want to do this network-buffering for packets originating from an 
> application. Is it possible to do it in the same way as above? Does it 
> do any damage to the host kernel? Can I get  a simple working example 
> for this?
>

Hi Shivam:

I haven't gone through the qdisc you mentioned, but it depends on a 
specific host network setup to work if I understand correctly.

Qemu support a native HA (COLO) which has a buffer filter.

Cc Chen for more information.

Thanks