Bug#770247: Fwd: ITP: mars -- Asynchronous Block-Level Storage Replication

[Gabriel Francisco <frc.gabriel@gmail.com>]

Forwarding to the ITP because I believe mars is an interesting project and to keep people in the loop.

-------- Forwarded Message --------

Subject:	Re: ITP: mars -- Asynchronous Block-Level Storage Replication
Date:	Thu, 21 Jan 2021 21:42:51 +0000
From:	Gabriel Francisco <frc.gabriel@gmail.com>
To:	Thomas Schöbel-Theuer <thomas@schoebel-theuer.de>, Francesco Paolo Lovergine <frankie@debian.org>

Hi, thanks for the updates!


Agree, getting mars into mainline will probably take some time, specially because of the required kernel patches. But I found that mars module can work fine with the vanilla/debian kernel when compiling it via dkms.


I tested manually, setting up a small volume and writing lots of stuff in it while checking the mars file in /proc (it really resembles mysql replication, yay!). I would like to have some tests running just to give me more confidence that I will not face any edge case. I'm trying to have the current test suite running, so far I have a work-in-progress at https://github.com/fgbreel/mars/tree/wip-dkms-run-test-suite where I'm setting up two virtual machines, installing the package and running the tests.


I felt that the existing test suite seems a bit rusty, but I don't mind. Having *something* to assert that mars dkms works makes me happy :)


I'll check out the link/new test suite you shared and see how it fit the whole picture. I just landed on a new job, but I'll try to provide an update soon.

Stay safe,

Gabriel Francisco


On 21/01/2021 19:58, Thomas Schöbel-Theuer wrote:

On 21/01/2021 19:08, Francesco Paolo Lovergine wrote:

 Having a single giant patch is not a big issue, of course not nice for
the kernel folks, but fast.

Misunderstanding: my talk about the "jumbo patch" was not about MARS or kernels, but about the _new_ test suite, written in _bash_ script.

Background: Gabriel had mentioned "the" test suite at github, although there are 2 different test suites in total, thus I was starting to explain something about the _new_ test suite.

Probably you don't need any of both test suites for making MARS availabe to Debian users.

The "old" test suite is in the mars repo you already know, in subdirectory test_suite/ . It is not developed anymore, because Frank Liepold left 1&1 in May 2014 (see "git log -- test_suite/" showing his last commit at his last working day).

You can find an outdated stage of the _new_ test suite at https://github.com/schoebel/test-suite (which is a _separate_ repo / project from MARS). My suggestion was to update this repo via a jumbo patch (saving a lot of work for me).

Getting MARS into kernel upstream is a completely different topic. Theoretically, it is just a new "driver", and changes practically _nothing_ at the rest of the kernel. I would be very lucky if it could be added to the kernel like a jumbo patch, since it adds only a bunch of new files. I already tried some years ago, but it got stuck.

I will retry once it runs on linux-next again (years ago it did, but then I had no time for updating it continuously).

Thank you very much,

Thomas