On 27. 07. 23 11:17, Klaus Darilion via bind-users wrote:
Hello!
Yesterday I made some tests transferring a zone with 50mio RRs to 35
Secondaries. I measured the time between:
-Primary logs "zone test/IN: sending notifies"
-Primary logs "client xxxx: transfer of 'test/IN': AXFR-style IXFR ended"
What makes we wonder is, that for several secondaries the XFR duration
is equally fast although these secondaries are globally distributed with
different RTTs and different VMs:
...
For example, there are 8 secondaries (Mumbai, LosAngeles, Melbourne,
Atlante, SaoPaulo...) to which the XFR took 2361 seconds.
Are there some mechanisms in Bind that put multiple XFRs together into a
common stream? Or do you have any other ideas how it come that several
XFRs are equally fast?
Are you sure all these transfers were _actually_ running in parallel?
I suspect it will boil down to some sort of configured limit like
transfers-out
transfers-in
transfers-per-ns
serial-query-rate
which cause some transfers to serialize and reduce parallelism.
See
https://bind9.readthedocs.io/en/latest/reference.html#namedconf-statement-serial-query-rate
https://bind9.readthedocs.io/en/latest/reference.html#namedconf-statement-transfers-in
options for tuning.
Consumption speed might be hampered by slow storage (zone journaling
does lots and lots of fsync()s, at least when you test IXFR).
--
Petr Špaček
Internet Systems Consortium
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