[nsd-users] Slow AXFR propagation to nsd server

[Anand Buddhdev]

On 17/08/2022 17:27, Zdeněk Nový via nsd-users wrote:

Hi Zdenek,

> 2022-08-16_14:29:01 xxxxxxxx nsd[1270460]: info:  notify for somedomain. 
> from 192.168.205.10 serial 1658932140
> 2022-08-16_14:29:07 xxxxxxxx nsd[2867429]: info:  xfrd: zone somedomain 
> committed "received update to serial 1658932140 at 2022-08-16T14:29:07 
> from 192.168.205.10 TSIG verified with key xxxxxxxxx"

This is the point at which the XFR has been written to disk, and NSD has 
initiated a reload.

> 2022-08-16_14:29:18 dfo5pub1 nsd[2867432]: info:  zone somedomain. 
> received update to serial 1658932140 at 2022-07-27T14:29:07 from 
> 192.168.205.10 TSIG verified with key xxxxxxxxx of 3045 bytes in 4.1e-05 
> seconds

It has taken NSD 11 seconds to update its internal memory structures 
with the new XFR.

> 2022-08-16_14:29:28 dfo5pub1 nsd[2867429]: info:  zone somedomain serial 
> 1658825141 is updated to 1658932140

10 more seconds later, the newly forked child processes have noticed the 
new zone data and are serving it.

> You can see, in this example, there is 10s delay between received update 
> and zone is updated actions.

Indeed. This is how NSD works. Since you have a lot of zones, it takes 
NSD quite some time to update its internal memory structures.

> I tried to remove the database with database: "", but there were no 
> significant change. I tried to setup the cpu affinity as well, but 
> without success, but I'd like to avoid of this complexity.

None of these things will do anything to speed up NSD's update of its 
memory structures.

> Do we have something wrong in our setup or does we reach the limitation 
> of the daemon. The server cpu graph shows us about 10% system time, 
> which seems weird to me as well and about 1% of user time., the 
> bandwidth is less than 5Mbps.
> 
> Can you give me some advice how to speed the process up?

I don't think you can make it any faster.

Regards,
Anand