From ZFS view a hardware raid behaves like a single disk. Due checksums ZFS will detect any data corruption. As there is no redundancy from ZFS view, the corruption cannot be repaired. The hardwareraid has redundancy but cannot detect the problem as it is not aware of the checksumms.
Another problem is the write hole problem of hardwarraid that can lead to a corrupt raid or filesystem on a crash during write. Even a cache + BBU cannot help.
Last problem is that ZFS want to guarantee that a commit with sync write is on disk. A cache on a disk or raid can give dataloss. A cache + BBU can help.
Another problem is the write hole problem of hardwarraid that can lead to a corrupt raid or filesystem on a crash during write. Even a cache + BBU cannot help.
Last problem is that ZFS want to guarantee that a commit with sync write is on disk. A cache on a disk or raid can give dataloss. A cache + BBU can help.