hosted by ip storage: best practices marc staimer, president & cds dragon slayer consulting...

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IP Storage: Best Practices

Marc Staimer, President & CDSDragon Slayer [email protected]

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Agenda

IP Storage Level Setting

File vs. Block Storage

FCIP, iFCP & iSCSI

Fiction & Facts about iSCSI

Storage Replication over WANs

Considerations for Designing IP Storage Networks

Questions

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There are 3 types:• Block Storage

iSCSI

• File Storage NAS

• Storage over WAN for business continuity = Block iSCSI FCIP iFCP

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iSCSI Storage• Block-based external storage on Ethernet

Vs. SCSI, USB, 1394, or FC

NAS or Network Attached Storage• File-based storage = NFS & CIFS

• No different than any other file server

• Requires block storage behind it

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By show of hands, what is acceptable packet loss for IP Block Storage on a LAN/WAN?

1) 1%

2) 5%

3) 10%

4) 0%

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Acceptable Packet Loss for IP Block Storage on a LAN/WAN

The Answer is:

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Block vs. File Storage

IP block data is unlike any other IP data

• Overwhelms most current LAN/WAN environments

• Incredible amounts of traffic

• Tolerates “ZERO” packet loss

• Very low latency

File storage = specialized file server

• NFS & CIFS

• Higher prioritization is required depending on app

• Volume of data may overwhelm untuned LAN/WAN

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FCIP, iFCP, iSCSI

FCIP

• Fibre Channel tunneled in TCP/IP

• IP transport between FC switches

iFCP

• IP header put on Fibre Channel frames for routing

• IP connection services for FC devices

iSCSI

• SCSI-3 mapped to TCP

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FCIPPt-to-Pt: Becomes “One” FC SAN• Disruptions pass SAN-to-SAN• Large FSPF database• PSS between SAN sites• Gateways between fabrics (blades or boxes)

Ethernet LAN/WAN Switches

Cisco MDS 9216

CNT UESR 3000

Brocade 3xxx

SAN 1

SAN 2

SAN 3

SAN 4

TCP/IPWAN

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iFCPPt-to-Multi-Pt• Device specific passing only the data that is required• Devices can appear in multiple individual SANs

The SANs themselves remain independent


SAN 1

SAN 2

SAN 3

SAN 4

TCP/IPWAN

McDATA/Nishan 3300

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Parable

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iSCSI: Ethernet-Based SAN

The Hype• Block storage on Ethernet

• Leverage current infrastructure investment &

knowledge base

• Lowers cost

• Eliminates headaches

• Ubiquitous

• Makes FC another Ethernet Road Kill

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iSCSI Defined IETF standard protocol

• Establishes & manages connections

• Carries storage (SCSI) blocks From initiators to storage

targets

Encapsulates SCSI blocks in TCP/IP

• Then tunneled in Ethernet

• iSCSI is to Ethernet as FCP is to Fibre Channel

Network application

• One infrastructure for LANs, NAS, & SANs

Ethernet Ethernet

FrameFrame

TCP/IP TCP/IP

PacketPacket

SCSI-3SCSI-3

TCP/IPTCP/IP

iSCSIiSCSI

NAS: File Storage

GbE Switch

Mission CriticalIA App Servers

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iSCSI Applications

NAS/SAN combined storage units

Entry level SANs

Limited budget SANs

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SAN Benefit Assertions of iSCSI

Reduced costs

• Professional services, implementation,

management & IT Staff time

Reduced complexity

Reduced Management

Increased Interoperability

Elimination of Multiple Networks

Unlimited SAN Distance

Equal or Better Performance

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Fiction & Facts about iSCSI Fiction

• Cost is lots < Fibre Channel (FC)

• Complexity is much < than FC

• Uses current infrastructure

• Requires no storage knowledge

• Is as fast as FC

• Will replace FC in Enterprise

• Easier to manage than FC

• Eliminates SAN distance limits Latency (delay) is not an

issue

Facts

• Known technology

• Costs are relatively < FC

Cycles or hardware

• Doesn’t require special HW

But benefits from it

• Latency (Delay) matters

Can’t be > 1 millisecond

• Deterministic routing

• Doesn’t require any-to-any

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Rating the iSCSI Value Props

Reduces or Eliminates SAN Professional Services

Lowers SAN Hardware Costs

Simplifies SAN Management

Eliminates Interoperability Issues

Converges SAN/LAN/MAN/WAN Fabric Infrastructure

Extends SANs over unlimited distances

Equal or better performance than FC SANs

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iSCSI Reality Check There are some real cost benefits for:

• NAS/SAN on the same fabric infrastructure

• SANs that don’t need the performance of FC

• Entry SANs that may not even need GigE and TOEs

Hype overshadows reality:

• GigE NICs with iSCSI and TOEs cost ~ same as FC HBAs

• FC ports & GigE ports on server motherboards

Makes port cost differences higher for GigE w/TOEs

• Very low cost simplified FC switches

Have erased much of the infrastructure HW differences

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Sample iSCSI Vendors

Switches

• Cisco

• Extreme

• Foundry

• Enterasys

• Nortel

• Lucent

• 3Com

Gateways

• Cisco

• McDATA

Silicon

• Adaptec

• Alacritech

• Intel

• Siliquent

• QLogic

Storage

NICs

• QLogic

• Intel

• Alacrite

ch

• Adaptec

• Emulex

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By show of hands, is latency (delay) important to iSCSI block storage?

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Is Latency Important to IP Block Storage?

The Answer is:• Yes, for the most part

• It also depends on application

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By show of hands, who believes that TOEs & iSOEs are an iSCSI block storage requirement?

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Are TOEs & iSOEs an iSCSI block storage requirement?

The Answer is: Not necessarily

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Spectrum of iSCSI Adapter Solutions

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Adapter Driver

TCP/IP

iSCSI

SCSI Port to OS

Software iSCSI“NIC + Driver”

Media Interface

Ethernet

Media Interface

Ethernet

Fast Path TCP/IP

Software iSCSIWith Partial TCP Off-load

TCP/IP

iSCSI

SCSI Port to OS

Media Interface

Ethernet

TCP/IP

iSCSI

Firmware TCPand iSCSI Off-load

SCSI Port to OS

= SW or FW

= Hardware

Media Interface

Ethernet

TCP/IP

iSCSI

Hardware TCP and Firmware iSCSI

Off-load

SCSI Port to OS

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iSCSI: No TOE

Definition• Std Ethernet NIC

TCP/IP & iSCSI Host-based in drivers

Who• Microsoft & Cisco

Advantages• Lowest cost• NICs available today• Easy integration with OS

Disadvantages • Lowest performance• High CPU load • High interrupts

Once/packet Many/ TCP segment

Adapter Driver

TCP/IP

iSCSI

SCSI Port to OS

Software iSCSI“NIC + Driver”

Media Interface

Ethernet

= SW or FW

= Hardware

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ter

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iSCSI: Little TOE Definition• NIC w/limited TOE

Packets in order & no frags Out of order etc. go to OS

Who• Alacritech

Advantages• Relatively low cost• Small layout (low profile card)• Good throughput w/pristine

Ethernet Disadvantages

• Out-of-order & frags < performance

• Interrupts Once/TCP segment Many/IO

• OS interface challenges

Media Interface

Ethernet

Fast Path TCP/IP

Software iSCSIW/Partial TCP Off-load

TCP/IP

iSCSI

SCSI Port to OS

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ter

= SW or FW

= Hardware

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iSCSI: Firmware TOE + iSOE

Definition• TCP/IP & iSCSI firmware

On-board processors Who• Adaptec, Intel, Emulex,

QLogic Advantages• Flexibility to change code• Low CPU load• Low interrupt load: < 1/IO

Disadvantages• No 10Gb scaling• Performance • Power, size

Media Interface

Ethernet

TCP/IP

iSCSI

Firmware TCPand iSCSI Off-load

SCSI Port to OS

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stA

dap

ter

= SW or FW

= Hardware

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iSCSI: Hardware TOE + iSOE Definition

• Hardware ASIC TCP/IP bulk data path iSCSI digest (CRC)

• iSCSI in processors

Who• QLogic, iReady

Advantages• Flexibility to change iSCSI code• Low CPU load• Low interrupt load < 1/IO• Performance, scaling to 10G

Disadvantages• Complex chip • Lack flexibility to change TCP

code

Media Interface

Ethernet

TCP/IP

iSCSI

Hardware TCP & Firmware iSCSI Off-load

SCSI Port to OS

= SW or FW

= Hardware

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A TOEs Impact on iSCSI

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By show of hands, who believes that iSCSI allows block storage to go unlimited distance?

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Will iSCSI allow block storage to go unlimited distance?

The Answer is: Yes & No• Latency is the limiting factor

• Application dependent Transactions cannot exceed 1ms one way (100

miles) Asynch replication is not distance dependent

“The speed of light, is not just a limit, it’s a law.”

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Key Block IP Storage Issues

Distance

• Latency

• WAN bandwidth utilization of IP

Security

• Encryption

• Access

Performance

• Must be = to, or > than current expectations

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Storage Replication over WANs

Issues• Good Citizen on Shared TCP/IP WANs

• Filling the pipe > 50%

• End-to-end throughput

Compression

TCP latency

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Changing Paradigm for Asynch Storage Replication

Native Storage GigE interfaces emerging

• EMC Symm5 and DMX are available today

• EMC CLARiiON in development

• Hitachi developing GigE for Lightning and Thunder

Software Replication Apps over native IP

• Leverages IP WAN already in place

• Eliminates SAN gateway requirement (FCIP or iFCP)

Significant < cost Mirror/Replication apps

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High Speed TCP/IP Data Transport Challenges

Optimized for

• Small payloads & relatively short distances

Employs inefficient

• Error recovery & session management techniques

Delivers poor bandwidth utilization

• For most high performance applications

• Usually < 30% efficiency at extended distances

• Even less as distance and bit errors increase

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Cost of Inefficiency

Higher Bandwidth Cost

• Despite < costs, high speed (DS3, OC3, etc) circuits = expensive DSC survey of 200 end-users• BW = 50-70 % of storage replication costs

Operational Inefficiencies

• Can’t complete within time window delaying production ops

• Explosion in data exacerbates the problem

• Current = specialized equipment & separate networks Can’t fully leveraging IP infrastructure = > costs

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Native GigE Replication: SRDF Adaptive Copy & SNAP/Asynch• Performance degrades starting at ~ 300 miles

At 500 miles performance degradation is noticeable & significant


TCP/IPWAN

EMC DMX

SAN

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NetEx HyperIP

Native GigE Replication: SRDF + RFC 3135

Adaptive Copy & SNAP/Asynch• RFC 3135 = TCP/IP Performance Enhancing Proxy• Up to satelite distances (46K miles roundtrip)• 90% + bandwidth utilization (T1/E1, DS3, OC3, OC12)• Plus 2 to 4 to 1 compression

Who• NetEx (HyperIP), Expand, NetCera, Digital Fountain


TCP/IPWAN

EMC DMX

SAN

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EMC SRDF Replication over WANs Replication Methodologies Illustrated


Cisco MDS 9216

CNT UESR 3000

Brocade 3xxx

TCP/IPWAN

McDATA/Nishan 3300

EMC DMX

NetEx HyperIP

= GigE

= FC

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Considerations for Designing IP Storage Networks

Separate LAN fabric• Minimally, separate VLAN

Layer 2 switching• Best latency for Ethernet switching

• Nothing less than GigE

Understand LUNs• Mapping and Masking

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Questions?

hosted by ip storage: best practices marc staimer, president & cds dragon slayer consulting...

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