My 4U JBOD NAS box noise is dominated by the goddamn 1U-style jet engine fans.

45 helium HDDs themselves are relatively quiet.

PS: I ditched non-Solaris ZFS several years ago after ZoL destroyed itself unable to mount RW and the community shrugged at glaring fragility. XFS + mdadm (raid10) are solid and work. Boring and reliable get less press, but I like working over not working. Maybe folks here run Sun Thumpers at home which would be a form of ZFS that works.