Install DNS-Only on server with 512 MB of RAM fails. How to force it?


Well-Known Member
Nov 5, 2001

I am trying to install cpanel DNS-Only on a small VPS with only 512 MB of RAM. The installer fails with this message:

( INFO): Checking RAM now...
(ERROR): cPanel, L.L.C. requires a minimum of 768 MB of RAM for your operating system.
(FATAL): Increase the server's total amount of RAM, and then reinstall cPanel & WHM.
Unfortunately, I am not able to allocate another 256 MB of RAM to this server. I tried using:

sh latest-dnsonly --force

But that did not work.

This server was previously running DNS-Only on CentOS 6 with 512MB of RAM with no problems. I am just trying to upgrade the server to CentOS 7...

The server will be used as a very small nameserver for only a few zones. I will disable MySQL and other non-essential services after the install is finished, as it isn't needed. I'm confident that DNS-Only can run on 512MB since it already was running with no problems....

How can I get past this fatal check?

Last edited:


Well-Known Member
May 22, 2020
cPanel Access Level
Root Administrator
Hi @electric,

I believe the ability to override RAM for DNS-Only is a feature request.

There does seem to be some older non-cPanel documentation and guides which describes how to override the RAM requirement but I'd just recommend just upgrading.
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Product Owner
Staff member
Nov 14, 2017
While you might be able to customize something, I can't provide you with any cPanel supported solution for this. It's below our system requirements which are there for a reason. I would also not be able to confirm that the server would run successfully on this little RAM.


Well-Known Member
Nov 5, 2001
It's below our system requirements which are there for a reason
The only reason I can think is that a swapfile will be required. (In our testing, the swapfile does not appear to be used for day-to-day zonefile serving.... it seems to only be used when upcp runs, yum updates, etc. so having a swapfile has very little impact on critical performance of serving DNS zones as fast as possible.)

In case anyone is interested, we are running several DNS-Only (v90.0.15) nameserver with only 512MB of RAM and there are no problems at all. (To reduce memory usage, we disabled services not needed in the WHM-->Service Configuration-->Service Manager page: MySQL Server, APNSPush, Eximstats, ModSecLog, RecentAuthedMailIpTracker, and cPBandwd.)

Here's one of our DNS-Only server's output from "top" and "free":

top - 10:04:43 up 63 days, 8:15, 1 user, load average: 0.04, 0.01, 0.01
Tasks: 41 total, 1 running, 40 sleeping, 0 stopped, 0 zombie
%Cpu(s): 1.0 us, 0.3 sy, 0.0 ni, 98.7 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem : 524288 total, 78368 free, 61024 used, 384896 buff/cache
KiB Swap: 524288 total, 496176 free, 28112 used. 306142 avail Mem

[[email protected] ~]# free -h
total used free shared buff/cache available
Mem: 512M 59M 76M 320K 375M 299M
Swap: 512M 27M 484M

This DNS-Only server handles around 40 zone lookups per second (according to dnstop) using PowerDNS. The VPS is allocated 1 CPU core E5-2620 @ 2GHz (no burst) with 20GB of SSD storage.

As long as you're ok with a swapfile being necessary (for upcp, etc.)... there seems to be no problem to have only 512MB of RAM.