Storage Networking Protocols Nicole Opferman CS 526 5/8/2006 Nicole SAN Protocols

Objectives Increase knowledge of storage networking industry Analyze the emerging storage networking protocols Learn about the SCSI and Fibre Channel protocols Determine how TOE fits in 5/8/2006 Nicole SAN Protocols

Storage Area Networks (SANs) High-speed network that connects servers to storage devices Any-to-any connection doesn’t require a dedicated connection between a server and storage component No limit to the amount of data that a server can access Many servers can share a storage unit made up of different storage devices Can be local or extended over large geographical distances 5/8/2006 Nicole SAN Protocols

SCSI Protocol Small Computer System Interface Standard interface and command set Promotes device independence, so it can be used on any hardware Used by OS for I/O communication with storage devices Commands are sent as blocks of data from an ‘initiator’ to a ‘target’ in parallel across copper cables 5/8/2006 Nicole SAN Protocols

Fibre Channel Protocol Performs most of its processing in the hardware High performance, reliable connectivity Efficient transfer of block data with minimal server intervention Storage interface to the OS allows HBAs to supply I/O processing Signals sent through twisted-pair copper wires or fiber optic cables Topologies: point-to-point, arbitrated loop, switched fabric 5/8/2006 Nicole SAN Protocols

iSCSI (Internet SCSI) Uses TCP/IP to transfer its data Carries SCSI commands over IP networks TCP/IP overhead during data transfers Much cheaper to implement than FC because it only requires an Ethernet interface IP-based SANs use the same networking technologies for both data and storage networks TCP/IP can run over nearly any type of physical network IP networks allow for location-independent data retrieval and storage, which Fibre Channel can’t do 5/8/2006 Nicole SAN Protocols

IP Network with iSCSI Devices Source: http://searchstorage.techtarget.com/gDefinition/0,294236,sid5_gci750136,00.html 5/8/2006 Nicole SAN Protocols

How iSCSI Works An end user or an application submits a request The OS generates the corresponding SCSI commands and data requests, which get encapsulated, and possibly encrypted A packet header is added to the resulting IP packets being sent across an Ethernet connection When a packet is received, it is decrypted (if needed) and separated into two parts: the SCSI command and the request The SCSI commands get sent on to the SCSI controller and then to the storage device Since iSCSI is bi-directional, the protocol is also used to return data in response to the original request 5/8/2006 Nicole SAN Protocols

TCP/IP Offload Engines (TOEs) The overhead of TCP/IP processing is the major deterrent to iSCSI storage networks High TCP overhead in an iSCSI SAN comes from establishing and terminating connections and acknowledging that packets were received PCI inefficiently transfers small bursts of data from the host across the bus to the network interface integrated circuits The TOE is a modern technology that is gaining popularity in high-speed Ethernet systems because it optimizes throughput by moving TCP/IP processing to a dedicated sub-system separate from the main host CPU TOE components are built into a circuit board, either the HBA or the NIC 5/8/2006 Nicole SAN Protocols

How TOEs work 5/8/2006 Nicole SAN Protocols Source: http://www.networkworld.com/techinsider/2003/0707techupdate.html 5/8/2006 Nicole SAN Protocols

Fibre Channel over IP (FCIP) “Fibre Channel tunneling” or “storage tunneling” FCIP tunnels FC data between SAN components over IP networks An IP infrastructure allows geographically distant SANs to be connected for a relatively low cost Much higher performance than iSCSI FCIP encapsulates Fibre Channel block data and then transports it over a TCP socket TCP/IP functions are necessary to set up connectivity between remote SANs 5/8/2006 Nicole SAN Protocols

Fibre Channel SAN 5/8/2006 Nicole SAN Protocols Source: http://www.redbooks.ibm.com/redbooks/SG245470/wwhelp/wwhimpl/java/html/wwhelp.htm 5/8/2006 Nicole SAN Protocols

iFCP (Internet FC Protocol) A derivation of FCIP, but iFCP is a routed (gateway-to-gateway) FC protocol Provides a way to pass data to and from Fibre Channel storage devices in a SAN, or by using TCP/IP in an Internet environment Can integrate existing Fibre Channel and SCSI networks into the Internet Has the ability to connect many FC devices to an IP network, combine FC SANs with IP networks, and allows end users to replace a SAN with a TCP/IP network In an iFCP setting, gateway devices are the midpoint between the FC initiators and target devices 5/8/2006 Nicole SAN Protocols

To wrap it up… FCIP, iSCSI, and iFCP are working towards universal data storage access Fibre Channel is the best choice for established, highly available storage networks iSCSI has the potential to provide wide area backup applications and remote access to storage networks TOEs make iSCSI a much more desirable choice FCIP can bridge SANs across the WAN iFCP is ideal for converting a Fibre Channel SAN to an IP SAN, or to update the configuration to allow a combination of both types of networks 5/8/2006 Nicole SAN Protocols