Many things has changed since previous default was set many years ago.
Nowadays 8KB does not allow adequate compression or even decent space
efficiency on many of pools due to 4KB disk physical block rounding,
especially on RAIDZ and DRAID. It effectively limits write throughput
to only 2-3GB/s (250-350K blocks/s) due to sync thread, allocation,
vdev queue and other block rate bottlenecks. It keeps L2ARC expensive
despite many optimizations and dedup just unrealistic.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Alexander Motin <mav@FreeBSD.org>
Closes#12406
72f0521aba