If you’re as paranoid as me about data integrity, SAS drives on a host adapter card in “Initiator Target” (IT) mode with write-cache on the disks disabled is the safest. It will degrade performance when writing many small files concurrently, but not as badly as with SATA drives. With a good error-correcting redundant system such as ZFS you can probably get away with enabled write cache in most cases. Until you can’t.