Package name: mars-dkms
Version: 0.1.09
Upstream Author: Thomas Schoebel-Theuer <tst@1und1.de>
URL: http://schoebel.github.io/mars/
License: GPL-2+, GFDL-1.3+
Description: Asynchronous Block-Level Storage Replication
MARS can be used to replicate Linux-based storage devices, or even whole
datacenters, over arbitrary distances (geo-redundancy).
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Main features:
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Anytime Consistency
Arbitrary Distances
Tolerates Flaky Networks
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MARS Light is almost a drop-in replacement for DRBD (block-level storage
replication). It runs as a Linux kernel module.
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In contrast to plain DRBD, it works asynchronously and over arbitrary
distances. Our internal 1&1 testing runs between datacenters in the US and
Europe. MARS uses very different technology under the hood, similar to
transaction logging of database systems.
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Reliability: application and replication are completely decoupled. Networking
problems (e.g. packet loss, bottlenecks) have no impact onto your application
at the primary side.
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Anytime Consistency: on a secondary node, its version of the underlying disk
device is always consistent in itself, but may be outdated (represent a
former state from the primary side). Thanks to incremental replication of the
transaction logfiles, usually the lag-behind will be only a few seconds, or
parts of a second.
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Synchronous or near-synchronous operating modes are planned for the future,
but are expected to work reliably only over short distances (less than 50km),
due to fundamental properties of distributed systems.
Note that the user reading this description need not be familiar with DRBD to understand it. Hence I would reverse this sentence to produce something like MARS Light is a block-level storage replication solution implemented in the form of a Linux kernel module. . It's almost a drop-in replacement for DRBD but it works asynchronously and over arbitrary distances. When a user reads the package description, "our" is a moot term for them at that time; at best, it would mean "Debian" which is clearly not true. Hence I'd refactor the long description making it as much neutral as possible, refining the above to become MARS Light is a block-level storage replication solution implemented in the form of a Linux kernel module. . It's almost a drop-in replacement for DRBD but it works asynchronously and over arbitrary distances using a technology similar to transaction logging of database systems. These two paragraphs sound OK if a bit too long. advertisement brief, not a package description.
Hi Konstantin, Thank you for your good description improvement suggestions. I completely agree with all of them. It was just a quick RFP where I copy- pasted upstream description as is. Of course it is not perfect but now, thanks to you, maintainer will have a pretty good ideas how to improve it.--- Good luck happens when preparedness meets opportunity.
Forwarding to the ITP because I believe mars is an interesting project and to keep people in the loop. 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