Elevate process and DNSONLY servers
Answered
I've got a couple of DNSONLY cPanel servers in a DNS cluster. Servers are running CentOS 7. Both servers are in production.
DNS Path Diagram (from one of the WHM servers):
cpanel.domain.tld
-> cpns1.domain.tld (DNS1: write-only role)
-> cpns2.domain.tld (DNS2: write-only role)
I need to upgrade both servers to Almalinux 8, and I'm going to use the Elevate script.
1)
I've read it's recommended to remove a DNSONLY server from the DNS cluster before upgrading it. That's what I'm going to do.
To be sure. There are a total of 5 WHM servers which use the DNS cluster. Does this mean I have to log in to every WHM server and manually remove the DNSONLY server from the DNS cluster?
2)
How will the DNS cluster and the DNS service work during the upgrade process?
For example, if a cPanel user is updating a domain zone during the upgrade process and there is only one DNS server on the DNS cluster at that moment? Will the zones be out of sync after the upgrade? How to deal with that?
Should I shut down the cPanel (port 2083) from the customers, so they can't do any zone changes during the upgrade?
3)
Do the DNS queries from outside work during the upgrade if one DNS server is not responding because of the upgrade?
4)
What if something goes wrong during the upgrade and I have to do a rollback from backups.
Is there any tool to check if the DNS cluster is in sync? Is there a tool which syncs the zones on both DNS servers? I mean in a situation where one DNS server might have an updated zone and the other one does not.
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Hey there! I wouldn't bother with any of that, as upgrading a DNSOnly system in that way is not supported. I would just create new DNSOnly servers, add them to the cluster. You can then remove the old servers and completely shut them off once you know the cluster is working.
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Elevate script doesn't support DNSONLY upgrades? I read this thread earlier and the user said it worked fine. Is something changed after that?
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If I create a new DNSONLY server and add it to the DNS cluster. After that I have to add the new DNS server to all our domains, right? That's out of the question. Or am I missing something how the process goes? Every domain has two NS records.
My goal is to replace the old cpns1.domain.tld and cpns2.domain.tld DNSONLY servers:
- keeping the old IP-addresses
- keeping the old server names
- keeping the data (all the zones)
- everything should change behind the scenes, no changes required to the domains.If the Elevate script is able to upgrade a DNSONLY server. Please answer the questions in my first post.
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I did confirm with the ELevate team that a DNSOnly upgrade should work just fine! I'm also going to see if we can get that added to the documentation somewhere to avoid future confusion.
For your specific questions:
1 - The only reason you may want to remove it is to avoid slowness of DNS queries. If a query gets directed to the server during the ELevate process it will just bounce to the next one, but of course there would be a slight delay there.
2 - I wouldn't expect this one to matter. DNSOnly machines could go offline for other reasons besides ELevate - in fact, that's the entire point of running a DNS cluster. There may be a brief period where things our out of sync when it first comes back online, but the cluster will handle that gracefully and will resync soon.
3 - Yes
4 - Yes - you could run syncall command as outlined here:
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Thank you cPRex. And thanks to the Elevate team. They have done a superior job with the script.
I've successfully upgraded the first DNSONLY server (cpns1.domain.tld, running CentOS 7) to Almalinux 8. I had one blocker. After that, Elevate script worked fine. Everything seemed fine after the upgrade. The DNS cluster is answering and working.
A few keynotes:
- I did not remove the cpns1.domain.tld server from the cluster
- I made a firewall rule to block access on cPanel port 2083. Just in case. I had that option.
- Upgrade process was fast. Downtime was minimal.The second server is waiting next.
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Nice - glad to hear it went so well!
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