Hi,
Thanks for reply...!
We have configured setMaxUDPOutstanding(65535) and still we are seeing backend
down, logs are showing frequently as below.
Timeout while waiting for the health check response from backend 192.168.1.1:53
Timeout while waiting for the health check response from backend 192.168.1.2:53
Please have a look at below dnsdist configuration and help us to find
misconfiguration (16 Listeners & 8+8 backends added as per vCPUs available (2
Socket x 8 Cores):
controlSocket('127.0.0.1:5199')
setKey("")
---- Listen addresses
addLocal('192.168.0.1:53', { reusePort=true })
addLocal('192.168.0.1:53', { reusePort=true })
addLocal('192.168.0.1:53', { reusePort=true })
addLocal('192.168.0.1:53', { reusePort=true })
addLocal('192.168.0.1:53', { reusePort=true })
addLocal('192.168.0.1:53', { reusePort=true })
addLocal('192.168.0.1:53', { reusePort=true })
addLocal('192.168.0.1:53', { reusePort=true })
addLocal('192.168.0.1:53', { reusePort=true })
addLocal('192.168.0.1:53', { reusePort=true })
addLocal('192.168.0.1:53', { reusePort=true })
addLocal('192.168.0.1:53', { reusePort=true })
addLocal('192.168.0.1:53', { reusePort=true })
addLocal('192.168.0.1:53', { reusePort=true })
addLocal('192.168.0.1:53', { reusePort=true })
addLocal('192.168.0.1:53', { reusePort=true })
---- Back-end server
newServer({address='192.168.1.1', maxCheckFailures=3, checkInterval=5,
weight=4, qps=40000, order=1})
newServer({address='192.168.1.1', maxCheckFailures=3, checkInterval=5,
weight=4, qps=40000, order=2})
newServer({address='192.168.1.1', maxCheckFailures=3, checkInterval=5,
weight=4, qps=40000, order=3})
newServer({address='192.168.1.1', maxCheckFailures=3, checkInterval=5,
weight=4, qps=40000, order=4})
newServer({address='192.168.1.1', maxCheckFailures=3, checkInterval=5,
weight=4, qps=40000, order=5})
newServer({address='192.168.1.1', maxCheckFailures=3, checkInterval=5,
weight=4, qps=40000, order=6})
newServer({address='192.168.1.1', maxCheckFailures=3, checkInterval=5,
weight=4, qps=40000, order=7})
newServer({address='192.168.1.1', maxCheckFailures=3, checkInterval=5,
weight=4, qps=40000, order=8})
newServer({address='192.168.1.2', maxCheckFailures=3, checkInterval=5,
weight=4, qps=40000, order=9})
newServer({address='192.168.1.2', maxCheckFailures=3, checkInterval=5,
weight=4, qps=40000, order=10})
newServer({address='192.168.1.2', maxCheckFailures=3, checkInterval=5,
weight=4, qps=40000, order=11})
newServer({address='192.168.1.2', maxCheckFailures=3, checkInterval=5,
weight=4, qps=40000, order=12})
newServer({address='192.168.1.2', maxCheckFailures=3, checkInterval=5,
weight=4, qps=40000, order=13})
newServer({address='192.168.1.2', maxCheckFailures=3, checkInterval=5,
weight=4, qps=40000, order=14})
newServer({address='192.168.1.2', maxCheckFailures=3, checkInterval=5,
weight=4, qps=40000, order=15})
newServer({address='192.168.1.2', maxCheckFailures=3, checkInterval=5,
weight=4, qps=40000, order=16})
setMaxUDPOutstanding(65535)
---- Server Load Balancing Policy
setServerPolicy(leastOutstanding)
---- Web-server
webserver('192.168.0.1:8083')
setWebserverConfig({acl='192.168.0.0/24', password='Secret'})
---- Customers Policy
customerACLs={'192.168.1.0/24'}
setACL(customerACLs)
pc = newPacketCache(300000, {maxTTL=86400, minTTL=0, temporaryFailureTTL=60,
staleTTL=60, dontAge=false})
getPool(""):setCache(pc)
setVerboseHealthChecks(true)
Servers Specs are as below:
Dnsdist LB Server Specs: 16 vCPUs, 16 GB RAM, Virtio NIC (10G) with 16
Multiqueues.
Backend bind9 servers Specs: 16 vCPUs, 16GM RAM, Virtio NIC (10G) with 16
Multiqueues.
We are trying to handle 500K qps (will increase hardware specs, If required) or
with above specs atleast 100K qps.
Regards,
Rais
-----Original Message-----
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To: [email protected]
Subject: dnsdist Digest, Vol 79, Issue 3
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Today's Topics:
1. dnsdist[29321]: Marking downstream IP:53 as 'down' (Rais Ahmed)
2. Re: dnsdist[29321]: Marking downstream IP:53 as 'down'
(Remi Gacogne)
----------------------------------------------------------------------
Message: 1
Date: Tue, 22 Mar 2022 23:00:25 +0000
From: Rais Ahmed <[email protected]>
To: "[email protected]" <[email protected]>
Subject: [dnsdist] dnsdist[29321]: Marking downstream IP:53 as 'down'
Message-ID:
<paxpr08mb70737e4e1ccefc4a7f61e1e6a0...@paxpr08mb7073.eurprd08.prod.outlook.com>
Content-Type: text/plain; charset="us-ascii"
Hi,
We have configured dnsdist instance to handle around 500k QPS, but we are
seeing downstream down frequently once QPS reached above 25k. below are the
logs which we found to relative issue.
dnsdist[29321]: Marking downstream server1 IP:53 as 'down'
dnsdist[29321]: Marking downstream server2 IP:53 as 'down'
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------------------------------
Message: 2
Date: Wed, 23 Mar 2022 10:32:22 +0100
From: Remi Gacogne <[email protected]>
To: Rais Ahmed <[email protected]>, "[email protected]"
<[email protected]>
Subject: Re: [dnsdist] dnsdist[29321]: Marking downstream IP:53 as
'down'
Message-ID: <[email protected]>
Content-Type: text/plain; charset=UTF-8; format=flowed
Hi,
> We have configured dnsdist instance to handle around 500k QPS, but we > are
> seeing downstream down frequently once QPS reached above 25k. below > are
> the logs which we found to relative issue.
>
> dnsdist[29321]: Marking downstream server1 IP:53 as 'down'
>
> dnsdist[29321]: Marking downstream server2 IP:53 as 'down'
You might be able to get more information about why the health-checks are
failing by adding setVerboseHealthChecks(true) to your configuration.
It usually happens because the backend is overwhelmed and needs to be tuned to
handle the load, but it might also be caused by a network issue, like a link
reaching its maximum capacity, or by dnsdist itself being overwhelmed and
needing tuning (like increasing the number of
newServer() directives, see [1]).
[1]:
https://dnsdist.org/advanced/tuning.html#udp-and-incoming-dns-over-https
Best regards,
--
Remi Gacogne
PowerDNS.COM BV - https://www.powerdns.com/
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