[Kea-users] Lease Tuning

[Darren Ankney]

Hi Scott,

In most situations, you should leave these numbers at their default.
The lease file cleanup merely cleans the log file of allocated leases
on the disk.  This is only used when Kea is restarted so that it can
read the leases into memory.  If you observe this file, you'll note
that Kea writes a line to it every time a lease is changed (allocated,
renewed, released).  As you can imagine this file can get quite large
leading to long startup times if not periodically cleaned.  The
default is to clean it every 3600 seconds (1 hour) by launching the
external lfc program.  This should be sufficient as Kea doesn't need
to actually do anything but launch the program.

As for reclaim-timer-wait-time
(https://kea.readthedocs.io/en/kea-2.4.0/arm/lease-expiration.html#configuring-lease-reclamation)
this controls how long Kea waits before looking for expired leases
again.  Unless you have a slow system, you probably don't need to
worry about adjusting this with only ~5000 active leases.  If you are
concerned, I recommend using `perfdhcp`
(https://kea.readthedocs.io/en/kea-2.4.0/man/perfdhcp.8.html) to test
your configuration / hardware before deployment.

Thank you,

Darren Ankney

On Tue, Nov 14, 2023 at 12:37 PM Scott Rakow <srsqrd at gmail.com> wrote:
>
> I have started the implementation of what could become a large number of users/pools in a Kea-DHCP4 (20 pools/5000+ IP's) and have some questions about how to estimate/calculate some of these values.
>
> How do I determine how long it takes to clean the memfile database?
>
> What is the best way to calculate the lfc-interval and reclaim-timer-wait-time? Is it based on the predicted number of IP's that could/can be used?
>
> Are there advantages/disadvantages to having a short or long interval/timer?
>
> Are the valid-lifetime, T1, and T2 values part of how to calculate these values?
>
> Thanks
> Scott Rakow
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