STORAGE
ARCHITECTURE/
MASTER):
Where IP and FC Storage
Fit in Your Enterprise
Randy Kerns
Senior Partner
The Evaluator Group
Agenda
 Storage Connection
•
•
Fibre Channel
IP
 NAS
 iSCSI
 Planning
 Usage
Storage connection
 Fibre Channel
•
Used in Storage Area Networks (SAN)
 Enterprise datacenter environments
 In SMB – primarily with packaged solution “SAN in a
Box”
•
•
Direct connection from servers to storage systems
Used in storage systems for drive connections
Fibre channel
 Targeted at block-level I/O for high
performance
 Heterogeneous storage and server attachment
 Nearly unlimited scaling of storage
•
•
capacity
performance (bandwidth)
 Centralized administration
 Shared resources – pooling of devices
 Enterprise class capabilities – RAS, capacity
planning, business continuity
Fibre channel (2)
Clients
Local Area Network
Servers
SAN
JBOD
Disk array
ATL
Storage connection
 Network Attached Storage (NAS)
•
Special purpose device to provide remote file system to other
servers on the network
•
Usually a kernel or thin server that supports NFS, CIFS, HTTP
and FTP
 some implement standard server and call it NAS
 single purpose devices are called appliances
•
Utilizes IP for connection protocol and UDP or TCP
NAS
 Simplicity – easy to install and administer
 High Availability – many NAS devices are fault tolerant
and support internal failover
 Scalability – most NAS devices can scale in capacity and
performance up to a point (upper limit)
 Connectivity – utilizes standard network infrastructures
(typically Ethernet) and supports multiple connections
NAS (2)
 Access – done with NFS and CIFS
 Data Sharing – a basic function of NAS for files
 Cost – significant competition has driven costs
down. Many offerings from wide range of
vendors
 Backup – beginning to see backup over SANs,
but many have integrated backup devices to
avoid LAN usage
NAS (3)
Workstation
Workstation
Host
Tower box
LAN
I/O Requests for
for File I/O using
NFS, CIFS
Server
Server owns storage
device and does block
level I/O
NAS
Storage
Disk array
Do you have NAS installed in:
30%
30%
1. Departments in larger
companies
2. Enterprise Data Center
20%
20%
3
4
3. Small to mid-size
business
4. None
0/0
1
2
Storage connection
 iSCSI – Internet SCSI
•
•
•
Use of SCSI commands over IP
Target is to provide block I/O using Ethernet infrastructure
No mechanism in Ethernet/IP to allow for commandresponse structure of SCSI
 SCSI is block oriented storage interface
 Both an interface and a protocol
•
Ethernet / IP has network characteristics
 No flow control – drops packets on congestion
 Packet size is limited – get smaller as contention
increases
 iSCSI attempts to work within these constraints
iSCSI
mapping
over IP
Open Systems Interconnect Model
Application
Presentation
Session
iSCSI
Transport
TCP
Network
IP
Abstraction of network for access by application. The
application will do a read or write operation either to a
device or a file.
Data transformation occurs to present in a uniform
manner. This is implemented with the application layer.
iSCSI is established as an application session to map
SCSI on top of TCP
Responsible for end-to-end delivery utilizing two services:
connection oriented (TCP) and connectionless (UDP).
Routing of data packets between systems with
intermediate systems. Usual protocol implement for this
is IP (Internet Protocol).
Data Link
Data transfer across medium including error checking,
forwarding and retransmission requests. Example is
Ethernet.
Physical
Type of communication medium (copper, fibre, RF),
signal modulation, bit encoding
iSCSI – Encapsulation
Ethernet
Header
IP
Header
TCP
Header
iSCSI
Header
Data
Up to 1,450 Bytes
CRC
Delivery of iSCSI Protocol Data Unit (PDU) to
contain state and control information for SCSI
Reliable transport software information for
delivery and ordering.
Internet Protocol for routing through a network
Physical network interface and control for Ethernet
iSCSI – Encapsulation mapping
SCSI Comand Descriptor Block and Data
iSCSI PDU
Header
IP Packet
iSCSI PDU
Data
Header
IP Packet
iSCSI PDU
Data
IP Packet
No Natural
Alignment for
Encapsulation
Header
IP Packet
Data
IP Packet
iSCSI usage
IP SAN Using iSCSI
Servers
Ethernet
Network
Ethernet
Switch
Storage
System
10/100
Gig-E
Sonet/SDH
ATM
Remote
Site
iSCSI usage (2)
iSCSI Connection for Stranded Servers
Servers
FC to IP Routers
Fibre
Channel
Fabric
Storage
Systems
Stranded Servers
If you plan on using iSCSI, will
it be for:
40%
1. An IP SAN
2. Connect stranded
servers
30%
30%
2
3
3. Both
0/0
1
Planning
 Understand requirements
•
•
•
Look at performance, security, cost, availability
Understand administrative issues and needs
Look at needs in the future
 Decide which solutions fit the requirements
•
•
Technology characteristics
Consider the economics
 Administrative costs
 Expansion costs
 Device / infrastructure costs
Usage
 Enterprise DataCenter market
•
Majority of companies have deployed FC SANs
 > 80% in some form
 > Half of storage in storage network
•
Most have single switch/director vendor for specific SAN
 Want to manage only one type
•
Many have only one storage vendor per SAN
 Because that’s the way salesmen sold it
•
NAS Gateways are seeing deployments
 Major vendors offering gateways
 New challenge for storage administrators
 Establishes presence for NAS in Enterprise Datacenters
•
Customer focus is now on storage management
Usage (2)
 Small to mid-size business
•
FC SAN is usually packaged “SAN in a box” solution
 No storage professionals to implement or manage a SAN
 Percentage-wise, a small amount of deployment
•
IP SANs are early in deployment
 Typically in very cost-sensitive environments
 Still storage administration to do
•
NAS is very successful in SMB market
 Also departmental and workgroup
 Fits well with requirements
•
Market open for many types of solutions
 Large and growing market with varying requirements
Summary
Choose wisely
•
•
•
•
Performance requirement – FC
Minimal administration and file I/O – choose NAS
Connect stranded server cheaply – iSCSI
Block I/O with minimal cost and not a high performance
requirement – iSCSI or packaged FC solution