STORAGE ARCHITECTURE/

MASTER): Where IP and FC Storage

Fit in Your Enterprise

Randy KernsSenior PartnerThe Evaluator Group

Storage Connection• Fibre Channel• IP

NAS iSCSI

PlanningUsage

Agenda

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

Storage connection

Targeted at block-level I/O for high performance

Heterogeneous storage and server attachment

Nearly unlimited scaling of storage• capacity• performance (bandwidth)

Centralized administrationShared resources – pooling of devicesEnterprise class capabilities – RAS,

capacity planning, business continuity

Fibre channel

Fibre channel (2)

Local Area Network

Servers

JBOD

SAN

Clients

Disk array ATL

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

Storage connection

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

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)

Disk array

Workstation Workstation Tower boxHost

LAN

Server

Storage

I/O Requests forfor File I/O using

NFS, CIFS

Server owns storagedevice and does block

level I/O

NAS

0/0

30% 30%

20% 20%

1 2 3 4

Do you have NAS installed in:

1. Departments in larger companies

2. Enterprise Data Center

3. Small to mid-size business

4. None

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 command-response

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

Storage connection

iSCSI mapping over IP Application

Presentation

Session

Transport

Network

Data Link

Physical Type of communication medium (copper, fibre, RF),signal modulation, bit encoding

Data transfer across medium including error checking,forwarding and retransmission requests. Example isEthernet.

Routing of data packets between systems withintermediate systems. Usual protocol implement for thisis IP (Internet Protocol).

Responsible for end-to-end delivery utilizing two services:connection oriented (TCP) and connectionless (UDP).

Abstraction of network for access by application. Theapplication will do a read or write operation either to adevice or a file.

Data transformation occurs to present in a uniformmanner. This is implemented with the application layer.

iSCSI is established as an application session to mapSCSI on top of TCP

Open Systems Interconnect Model

IP

TCP

iSCSI

iSCSIHeader

TCPHeader

IPHeader

EthernetHeader

DataUp 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

iSCSI – Encapsulation mapping

SCSI Comand Descriptor Block and Data

Header Data

iSCSI PDU

Header Data

iSCSI PDU

Header Data

iSCSI PDU

IP Packet IP Packet IP Packet IP Packet IP Packet

No NaturalAlignment forEncapsulation

iSCSI usage

RemoteSite

Network

10/100Gig-E

Sonet/SDHATM

EthernetSwitch

Servers

StorageSystem

IP SAN Using iSCSI

Ethernet

iSCSI usage (2)

FibreChannelFabric

Servers

StorageSystems

FC to IP Routers

iSCSI Connection for Stranded Servers

Stranded Servers

0/0

40%

30% 30%

1 2 3

If you plan on using iSCSI, will it be for:

1. An IP SAN

2. Connect stranded servers

3. Both

PlanningUnderstand 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

UsageEnterprise 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

SummaryChoose 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