1. HBA (Host Bus Adapter)

2. SAN (Storage Area Network) vs. NAS (Network Attached Storage)



 1. HBA (Host Bus Adapter)

A host bus adapter (HBA) is a circuit board and/or integrated circuit adapter that provides input/output (I/O) processing and physical connectivity between a server and a storage device. Because the HBA relieves the host microprocessor of both data storage and retrieval tasks, it can improve the server's performance time. An HBA and its associated disk subsystems are sometimes referred to as a disk channel.


2. SAN (Storage Area Network) vs. NAS (Network Attached Storage)

A SAN is a local network of multiple devices that operats on disk blocks while a NAS is a single storage device that operats on data files. Please see below for other differences:

ProtocolEncapsulated SCSITCP/IP and NFS/CIFS/HTTP
Device AttachmentsOnly devices with SCSI Fibre channel can connect to a SAN.Any machine that can connect to the LAN can use NFS, CIFS or HTTP to connect to a NAS and share files 
Data IdentificationBy disk block number and transfers raw disk blocksBy file name and byte offsets, transfers file data and handles security, user authentication and file locking 
Information SharingOS dependent Allows greater information sharing esp between disparate OS such as Unix and NT
File System ManagementBy Servers By NAS head unit
Backups and MirrorsRequires block by block copyDone on files, not blocks
 WiresFibre ChannelEthernet, FDDI, ATM