Host adapter Part 1
RAID Recovery - Host adapter
A host adapter, also known as host bus adapter (HBA) is one of the components that connect a host system to other network or storage devices. Host adapters mostly connect SCSI, Fiber Channel and eSATA devices.
SCSI host adapter
An SCSI host adapter is used to connect an SCSI bus to a computer. It acts as a gateway between the SCSI bus and the internal PC’s I/O bus. HBA responds to commands and transfers data between devices on the bus and the computer. Modern HBAs are provided with all the electronics and firmware required to execute SCSI transactions. It also includes a BIOS unit that allows the host system to boot from the SCSI device.
In a parallel SCSI subsystem, a host adapter is given the ID 7, which gives the highest priority on the SCSI bus. The host adapter also issues commands to other SCSI devices, thus it acts as an SCSI initiator. A computer may contain more than one host adapter, which can result in greater number of SCSI devices available.
Currently, companies like ATTO Technology, Adaptec, and LSI manufacture PCIe SCSI adapters. These adapters find application in new Apple Mac, Intel PCs and low-end motherboards that do not have SCSI support due to their SAS and/or SATA connectivity.
Fiber Channel
Fiber Channel host bus adapters are available for all major computer architectures including PCI. HBAs are available with different speeds: 1gigabit per second (Gbps), 2 Gbps, 4 Gbps, 8 Gbps, 10 Gbps and 20 Gbps. Each host adapter is given a unique World Wide Name (WWN), similar to an Ethernet MAC address.
