[nsd-users] Question about "store-ixfr"

[Willem Toorop]

Op 11-12-2023 om 12:19 schreef Anand Buddhdev via nsd-users:

> Hi NSD developers,
Hi Anand,
>
> I have been experimenting with the "store-ixfr" feature in NSD. I have 
> a configuration with:
>
> server:
>   zonefiles-write: 0
>
> pattern:
>   store-ixfr: yes
>
> With this configuration, NSD transfers zones from a primary, and keeps 
> them in RAM. When the zones are updated, it receives and stores the 
> IXFR in RAM too. I can query NSD with the IXFR qtype, and it replies 
> with the appropriate difference records. Neither the zone, nor the 
> IXFRs are ever written to disk.
That is correct. The zone and the IXFRs can be written to disk (for 
inspection) with `nsd-control write`, but serving the IXFRs is from RAM.
> This means that NSD is using RAM for the IXFRs. Could you confirm that 
> NSD with the "store-ixfr" option set to "yes" will use more RAM?

That is correct. The IXFRs are stored in RAM in wireformat which is 
quite memory efficient and has much less overhead than the resource 
records in the in-memory database.

You can further control the maximum memory usage of the IXFRs with the 
`ixfr-number:` and `ixfr-size:` parameters (which limits the maximum 
number of IXFRs to store and the maximum size for each IXFR).

Regards,

-- Willem

>
> Regards,
> Anand
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