Transcript Storage Networking Protocols

Storage Networking
Protocols
Nicole Opferman
CS 526
5/8/2006
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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
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Storage Area Networks (SANs)
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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
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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
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Fibre Channel Protocol
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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
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iSCSI (Internet SCSI)
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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
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IP Network with iSCSI Devices
Source: http://searchstorage.techtarget.com/gDefinition/0,294236,sid5_gci750136,00.html
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How iSCSI Works
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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
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TCP/IP Offload Engines (TOEs)
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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
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How TOEs work
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Source: http://www.networkworld.com/techinsider/2003/0707techupdate.html
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Fibre Channel over IP (FCIP)
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“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
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Fibre Channel SAN
Source: http://www.redbooks.ibm.com/redbooks/SG245470/wwhelp/wwhimpl/java/html/wwhelp.htm
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iFCP (Internet FC Protocol)
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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
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To wrap it up…
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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
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