[DRBD-user] Is it free?

Julien Escario julien.escario at altinea.fr
Wed Aug 7 18:48:05 CEST 2019

Sorry, I won't answer to any of your questions (as I'm not using DRBD
for Kubernetes) but to anwser to your first question : Yes, DRBD/Linstor
is completely free and a really nice piece of software.

But as it's free, we'll have to learn most caveats (and there is) by
yourself, debug by yourself and after that, if possible, contribute.

So if you're askign for really precise questions, sometimes, someone
from Linbit is kind enough to answer or is interested as your concern
could also be a bug, but most of the time, you'll have to test and debug
(your setup) by yourself or wait for the community to give you advices.

That's how the game is played for open and/or free software.


P.S. : I tried to setup DRBD over wireguard and I confirm you'll have
far less througput and more latency (and CPU usage) than with
'classical' IP. It could be enough, depends on your needs.

Oh, and remember : if your setup is correct, all reads operations are
made for your LOCAL storage. Only writes are replicated (and rely highly
on latency for protocols B & C). Hint : there's not use case for protocol B.

Le 07/08/2019 à 16:01, Vito Botta a écrit :
> Hi Roland! Thanks for your reply! I didn't get a notification, I just noticed it while checking the archives in the browser. So I hope this email updates the thread (never used this so not sure how it works :D).
> Thanks for the answers! I did more tests with replication and also changed the set up to use thin pools for thin provisioning and snapshots. All seems to work great.
> When I was setting it up again in Kubernetes, I found that the CSI yaml on Github references images for the 0.7.0 version not yet available on Quay, so I had to use 0.6.4 for now.
> A few more questions if you don't mind:
> - How do I handle upgrades of the Kubernetes components? Is it enough to just apply the new version of the yaml manifests or do I need to do something else?
> - What about upgrades to Linstor itself? Do I just upgrade packages when new ones are available in the apt repo or do I need to do something else? Will upgrading cause disruption to volumes in use? I am scared that an apt dist-upgrade may screw things up with storage, cause split brains or whatever.
> - From reading the docs I am not sure of what is the default "anti split-brain" configuration. Does Linstor recover by itself by default? 
> - I am trying to use Linstor on top of a Wireguard VPN, since I am looking to encrypt all the traffic between the nodes  - my provider Hetzner Cloud has private networking but somehow they recommend using encryption to protect sensitive data. When using Wireguard, benchmarks in a replicated setup show 1/3 lower write speed compared to running without VPN, at 40 to ~66 MB/sec or so. Is this OK for a good replication and for use with databases (MySQL) or is it too slow? Without VPN I was getting 100 MB/sec or more...
> Thanks!
> Vito
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