Hi,
https://kea.readthedocs.io/en/latest/arm/admin.html#upgrading-a-mysql-database-from-an-earlier-version-of-kea
There is a correction to the warning that warrants investigation:
a value of =2 (or even =0) is only a risk on *host* (kernel) crash. The
only thing that changes is that mysql/mariadb will not execute an
fsync() as frequently. So the stability of kea has no effect here.
Writes are still done in-order etc. However, when using replication,
it's pretty much a guarantee that you'll need to rebuild the crashed
host from the replica. The WAL is also affected by same and due to lack
of fsync() write-ordering (which is important for resilience) is not
guaranteed.
Someone may just want to look into the documentation here.
If kea uses multiple-threads towards mysql/mariadb, group commits is
another way to boost performance, this can be achieved by just
increasing the concurrency of threads towards mysql/mariadb - a bunch of
other parameters (like max connections etc) may also need to be tweaked.
The single biggest win for mysql/mariadb is a battery-backed
write-behind raid controller.
Compared to KEA I consider the Linux kernel to be significantly more
stable, however, crashes do happen, but please be sure that the
documentation reflects correctly, kea crashing has no effect on
mysql/mariadb consistency, and even mysql/mariadb crashes (should afaik)
not impact this stability, only host crashes where issued write()s don't
make it to disk.
Kind regards,
Jaco
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