The document discusses different types of storage networks including direct attached storage (DAS), network attached storage (NAS), storage area networks (SANs) using Fibre Channel (FC) or iSCSI, and Fibre Channel over Ethernet (FCoE). DAS connects storage directly to servers but has limitations. NAS uses a traditional LAN to share storage files between servers but has performance limitations. SANs allow block-level access to centralized storage using high-speed FC networks or iSCSI over Ethernet. FCoE encapsulates FC frames in Ethernet to converge network traffic.

1. Storage Networks
The use Network Concepts to
expand the Data Storage.
By Ahmed Nour
1 For (S)

2. Why Storage Is Important
• The growing demands for more data by time.
• The Data storage requirements for legal
regulations.
• The increase demand of paperless workplaces.
• The growth of file and Database sizes over the
years .
2 For (S)

3. Direct Attached Storage
The basic model for storage was the Direct attached storage in
which each server have its own Data connected to it. The I/O
technique used in this connection was the Small Computer
System Interface (SCSI)
3 For (S)

4. Small Computer Serial Interface
It’s the standard way to connect the Disks to the Servers , it's responsible
for performing the read , write Commands of the Operating system on the
Disk, also it uses a Bus (16 Bin). It has some limitations
• The maximum SCSI cable length is 25 Meter
• The Maximum Number of Attached Devices is 16 Device
• It's difficult to connect more than one servers to a same Disk which is
required to maintain the High availability.
4 For (S)

5. Storage networks
Network by definition is connecting two or more computers to
allow resource sharing and enhance communication. And the
resource that we need to share is the Storage.
5 For (S)

6. Network Attached Storage
Using the Traditional LAN, Assign a HUGE
Storage to a server and Share this storage to the
other servers and desktop by a well-known file
sharing protocol (NFS and CIFS).
6 For (S)

7. NFS and CIFS
• Network File system (NFS )
– is an application layer protocol was initially created By SUN Microsystem (NFS sv2 RFC
1094) on march 1989. In depends originally in RPC. in which the a machine can run some
procedures in a remote machines . Used to share a folder to UNIX and Linux machines .
the current version is NFS sv3
• Common Internet File System (CIFS)
– intended to provide an open cross-platform mechanism for client systems to request file and print services
from server systems over a network. It is based on the standard Server Message Block (SMB) protocol widely
in use by personal computers and workstations running a wide variety of operating systems but widly used
with MS Windows Operating systems .
7 For (S)

8. How NFS and CIFS work
8 For (S)

9. NAS Limitation and Problems
• It's a File level technique not a Block level one .
• By design the required file from the san must be
processed in the NAS Server or in the NAS
Gateway in order to transfer it to the client
• The Known Protocols for File shearing (NFS/CIFS)
use the TCP/IP stack which by default make a
process overhead in the NAS Servers and Client.
• At the end of the day the The NAS server or NAS
Gateway it's a server with a limited network and
processing capacity.
9 For (S)

10. Storage Area Networks
• As discussed before we use a network Concept to
Solve the problem of Storage Limitation In the
DAS we use the LAN in order to share a Specific
File or Directory to a server and this is suitable for
file sharing applications but not for Intensive I/O
applications such as Databases
• The next step is to find another Network that
carry the SCSI commands Directly from the OS to
the Storage system , this network must be FAST
and reliable one
10 For (S)

11. Fibre Channel SAN
• Fiber Channel is a multi-layered network, based on a series of American
National Standards Institute (ANSI) standards which define characteristics
and functions For moving data across the network. These include
definitions of physical Interfaces, such as cabling, distances and signaling;
data encoding and link Controls; data delivery in terms of frames, flow
control and classes of service ,Common services, and protocol interfaces.
Why Fiber Channel
• Serial transmission for high speed and long distances
• Low rate of transmission errors
• Low delay (latency) of the transmitted data
• Implementation of the Fiber Channel Protocol (FCP) in hardware on
HBA cards to free up the server CPUs
11 For (S)

12. Fibre Channel Connectivity
• Point to point connection, Bi-direction Connection between 2 devices only
• Arbitrated Loop connection, a unidirectional connection form a Ring , in
which only 2 devices can communicate at a time
• Fabric connection, a unidirectional connection that lets all the devices to
communicate in the same time using a Switch (Fabric Switch)
12 For (S)

13. Fibre Channel Node Types
Port Type Function
N-Port "N for node" port for servers or storage device can work for Point – to –
point or fabric topology
F-Port "F for fabric" a fabric switch port can communicate with N-ports
L-Port "L for Loop" an arbitrated loop port
NL-port Modern Ports can work both as a N-port or L-port
FL-Port Modern Ports can work as F-port or L-port
E-port "E for Extended" Ports used in the fiber switches to link 2 switches
G-port "G for generic " modern switches use G-ports to configure itself
automatically
B-port "B for Bridge " used to link the switch to a different protocol or network
13 For (S)

14. Fibre Channel Protocol Stack
14 For (S)

15. Fibre Channel Frame
• FC frame is 2148 bytes maximum
• 24 byte Header
• Source / Destination address
• Type indicates the type of frame (Data or Control)
• Sequence count , ID
• Exchange ID
15 For (S)

16. Fibre Channel Disadvantages
• Complexity
• Very expensive
• Needs a totally separated infrastructure to
build a storage system in the data center.
16 For (S)

17. iSCSI SAN
iSCSI is a block-level protocol that encapsulates SCSI
commands into TCP/IP packets, and thereby
leverages the investment in existing IP networks.
The iSCSI architecture is similar to client/server
architecture. In this case, the client is an initiator
that issues an I/O request and the server is a target
(such as a device in a storage system). This
architecture can be used over IP networks to
provide distance extension. This can be
implemented between routers, host-to-switch .
17 For (S)

18. iScsi Protocol
18 For (S)

19. iSCSI Disadvantages
The main problems in the ISCSI SAN is the
performance . The ISCSI By default use the
TCP/IP stack which make an overhead on the
CPU of the system, and increase the latency
comparing with the Fibre Channel SAN.
19 For (S)

20. Fibre Channel o Ethernet
Fibre channel over Ethernet, or FCoE is a new storage
networking protocol that supports Fibre Channel
natively over Ethernet. FCoE encapsulates Fibre
Channel Frames into Ethernet frames , allowing them
to run with traditional Internet Protocol .
The main requirement for FCoE
• Converged Network Adaptor (CNA) which act as Traditional NIC and
HBA at the same time
• FCoE Switch which is a network device that will connect to existing
LAN and SAN environments.
• The Link that FCoE traffic uses must provide the same level of
lossless behavior that can be found with fibre channel environment
and this could be done using the 10G Ethernet devices .
20 For (S)

21. FCoE Protocol Stack
21 For (S)

22. Conclusion
As Discussed Using the Network Concepts in
order to get over the traditional Storage
limitation is a very successful , it gives the ablilty
to consolidate the storages into a centralized
devices which are easy to manage , make the
backup very easy to handle makes its possible to
create an effective Disaster recovery sites , the
new technology of the FCoE SAN expected to
unify the network traffic of the data centers .
22 For (S)

23. Refrences
• U. Troppens, R. Erkens, W Muller-Friedt, R. Wolafka, N. Haustein,,“Storage Area
Networks Explained, Basics and Application of Fibre Channel
SAN, NAS, iSCSI, Infiniband and FCoE”, Second Edition, pp.59-100, 2009. John
Wiley and Sons Ltd., ISBN: 978-0-470-74143-6.
• Wikipedia For Fibre Channel Protocol
http://en.wikipedia.org/wiki/Internet_Fibre_Channel_Protocol
• Fibre Channel over Ethernet: A Beginners Perspective, Harshada Kshirsagar, Pooja
Ramrakhyani, Tejashri Vinode, 2011
• Fibre Channel over Ethernet Detailed Review White paper 2011
• IBM Redbook Introduction to Storage Area Network 2006
• Fibre Channel Fundamentals by Tom Weimer white paper
• Storage network industry assoistaion :www.SNIA.org
23 For (S)