When using a Host Bus Adapter (HBA) in a system that relies on software-managed redundancy, such as a NAS or server running ZFS, it is highly recommended that the HBA be flashed to IT Mode (Initiator Target mode). This mode disables any hardware RAID functionality and ensures that the operating system has direct, unaltered access to each individual drive. This is crucial for ZFS, which handles redundancy, integrity checking, and data repair entirely in software. If the HBA abstracts or modifies drive behavior, it can interfere with ZFS's ability to detect and correct data corruption, undermining the reliability of the entire storage pool. By using IT Mode, the system gains full visibility and control over every disk, enabling ZFS to manage its advanced features, such as checksumming, copy-on-write, RAID-Z, and self-healing capabilities, without interference. This setup is ideal for platforms like TrueNAS, Proxmox, or Linux servers where ZFS is used for robust, fault-tolerant storage.
