[Pdns-users] Question about Powerdns remote database backend best practices

[Jianan Wang]

Hi Chris,

Thanks for your detailed explanation on the scaling plan for power dns
deployment! It is very helpful from my current standing point, where we use
mostly bind based solutions and replication is more through axfr/ixfr.
Since it is pretty inspiring, I would like to follow up with some question
if you would not mind:

(1) Let's say you have master location A and B serving as writer, so it
means location C, D's local regional zone will also be written into
location A & B's dns instance? Sounds like the trade-off is between
simplicity of management compared to write availability for non-master
locations. Is the location you mentioned more like within a country or
world-wide?

(2) In your deployment here, it seems like your authoritative servers are
the ones being replicated, and you will have local resolvers pointing to
them behind the dnslist pairs you mentioned, right?

(3) I bet managing 5 million zones will be a pretty complicated question,
so just curious are you guys more a UI based management or git based
management in this case?

(4) Is there any good practice to manage the mysql instance ip? Are you
using lvs, vip style or ip anycast solution to point to master so it would
be free of changes? Normally we use domain names so that changing ip of
mysql instance will not impact all the services. However, since powerdns is
relying on this database anyways, meaning we could only use ip or dns
served by other instances.

Thanks for your help!
Jianan.

On Tue, Nov 17, 2020 at 10:11 PM Chris <mail at gbe0.com> wrote:

> Hi,
>
> The way I scale it out (this is scaled out to 12 locations currently):
>
> We picked 2 of our large locations to act as master locations. These 2
> different locations have an active/standby mariadb server cluster using
> corosync/drbd (so only 1 server in each location is master at a time). The
> two locations are setup as master/master (mysql replication). These are the
> servers for which all write changes are applied to. I only put them in two
> locations as this is much easier to manage and cuts down on replication
> problems.
>
> Each of the 12 locations we are in then has at least a pair of servers for
> PowerDNS. Each of these servers has their own individual copy of the MySQL
> DB; their copy is read only and they replicate it from the master servers.
> We only use MySQL to replicate the databases, we don't handle that at the
> DNS level (eg. axfr/ixfr). This way if the masters are taken offline (since
> they are only in two locations) at least DNS continues to work from the
> read only copy without changes. It would have to be a very bad day for all
> 4 master servers to do be dead anyway.
>
> Each of the 12 locations also has at least a pair of dnsdist frontends to
> accept queries from clients and direct it to the various PowerDNS backends.
>
> There is a bit more to it (delayed slaves for DR purposes, different
> local/remote pools for dnsdist etc.) of course, but thats the basics.
>
> We have over 5 million zones and over 40 million records (plus additional
> things like DNSSEC keys, metadata entries and so on) and so far this has
> scaled nicely for us.
>
>
> ------------------------------
> *From:* Pdns-users <pdns-users-bounces at mailman.powerdns.com> on behalf of
> Jianan Wang via Pdns-users <pdns-users at mailman.powerdns.com>
> *Sent:* Wednesday, 18 November 2020 00:05
> *To:* pdns-users at mailman.powerdns.com <pdns-users at mailman.powerdns.com>
> *Subject:* Re: [Pdns-users] Question about Powerdns remote database
> backend best practices
>
> Hi Thomas,
>
> Thanks for your response on this! IIUC, what you recommend is still having
> MySQL and PowerDNS created on one instance and scale the instance setup
> horizontally? If that’s the case, will the MySQL on the single node be
> bounded by its resources locally to scale when we have a lot of records?
>
> Thanks.
> Jianan.--
> Jianan Wang
>
>
>

-- 
Jianan Wang
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