Beyond NAS and SAN:The Evolution of Storage

Marc FarleyAuthorBuilding Storage Networks

What We’ll Do

Analyze storage network functions

Apply these functions in NAS and SANs

Observe market pressures forcing

changes

Identify evolving architectures

Fundamental Functions of Storage Networks

Wiring• Fibre Channel. Parallel SCSI, Ethernet, IP

Storing• Devices & Subsystems, I/O Controllers,

Virtualization SW & HW (RAID, Volume Managers,

Mirroring)

Filing• File systems, Databases, Backup, Replication

Building Blocks

WiringStoringStoring

FilingFiling

Traditional SAN Functional Distribution

Host SystemStorage

SubsystemFibre Channel

Network

HBA

Building Blocks

Controller

WiringStoringStoring

Traditional NAS Functional Distribution

Client System File ServerSystem

LAN

FilingFilingFilingFilingFilingFiling

NICInternal Bus

Building Blocks

Wiring: Physical & Logical Parts

Physical = Cabling and Network Hardware• signaling, encoding, error detection

Logical = Algorithms, Addressing,

Protocols and Services• access methods, flow control (buffer management)

• addressing, naming, topology management, routing

• filtering, zoning

• gateway, bridging and tunneling services

Building Blocks

Wiring: Fibre Channel and i-SCSI

Functionally equivalent as wiring technologies

More of a business issue than a technology

issue

Question: Will i-SCSI SANs be implemented as

distinct networks or grow as part of the

existing Ethernet/IP infrastructure?

i-SCSI leverage might be less than expected

- but it might be good enough

Building Blocks

Wiring: Separate SANs or Bigger LANs?

LAN

LAN SANGood Idea

An Question for the Audience…..

What is the best routing method for

storage traffic?• To date, storage networks have borrowed from IP

networking

• OSPF in IP networks (NAS) & FSPF in Fibre Channel

• What do you want?

• Fast recovery & optimal availability

– OR

• Compatibility with IP routing

An Idea

Storing

Block level operations• storage block addressing

• store, retrieve, status, resource reservation

Subsystems and Virtual Devices• block translation, mirroring, multiple ports, LUN masking

I/O commands between initiators and targets• SCSI, serial SCSI, SCSI adaptations, IDE

• Error correction reallyreally happens here

Building Blocks

Storing on Steroids: Virtualization

Virtualization techniques expand and

extend the capabilities of devices and

subsystems

Virtualization as a storing level function

has no ability to manage anything about

its contents

VirtualStorage

Physical Devices

Filing

Representation of data• files, directories, tables, records

Storage data structure (block address

layout) • equalized performance, maintain free blocks

System kernel integration• kernel manages time, file system manages space

File semantics• Open, close, update, delete, block range operations

Building Blocks

The Fundamental Role of Filing

Manage the use of the storing address

space

Building Blocks

StoringStoringFilingFiling

Internal Functions in Filing

Data View

MetadataData

Structure

NAS & SAN REDUX

SANs are the Application of Storing Functions Over a Network

The Caveat: SANS do not convey any

knowledge of data structures • & there is no way to provide data-level managementGotcha

StoringStoring Functions

Initiators Targets

Storing

Network

Virtualization Creates Storing Structures

Block Data

Initiators Virtual Targets

Storing

Network

Storing

Physical Devices

But not data

structures

NAS: The Application of Filing Functions over a Network

The Caveat: ‘Loose wiring’ for

I/O intensive computing

Gotcha

Filing Functions

Clients Servers

FilingFiling FilingFiling

Network

Challenge for NAS: Distribute Filing Functions & Reinforce the Wiring

File Data

Clients ServersNetwork

Storage Network Requirements

Market Needs

Integrity

Recoverability

Security

Availability

Manageability (Scalability)

Best Practice

Data Integrity Must be Maintained

Error free transmissions• Fiber optic cabling

Data segregation is a good thing• Who wants a Battle Royale over data?

• Any to any connectivity is not required

• Storage networks differ a lot from data networks

• Zoning, masking and fencing are band-aids

for existing architectural weaknesses

• Filing enforces data integrity through locking

Gotcha

Data Recoverability = Redundancy

Data redundancy system redundancy

Mirroring is fast, but relatively inefficient • Extended distance mirrors are “open territory”

• System buffer management is a caveat

Data structures must have integrity• Journalled file systems, database commitments

File system intelligence is most efficient• Serverless backup, data snapshots, replication

Gotcha

Security - the Great Afterthought

Protecting Data From Theft

File systems have done this for decades• System-login is the gatekeeper

There are no constructs for storing-level

security

Wiring-level security can be done, but is slow

Encryption is S-L-O-W for I/O• IP-SEC may provide a method

Gotcha

Remember the Good Old Days of SCSI?

Data integrity was less exposed with

Parallel SCSI • Human error was far less likely

• Storage was not accessible to hackers

Processing power on the storage end is

needed to provide security functions

Data Availability

Remove the system as a bottleneck• (And integrity and security become more suspect)

Availability doesn’t necessarily mean

“seamless”• Single servers in SANs can failover using redundant paths

• NAS network failures must re-connect

Data sharing can provide availability • NAS file locking can ensure integrity for server farms

• Data sharing in SANs is expensive and complex

The Fine Print in Scalability

Maxed-out NAS requires additional mount

points• Users and application configurations must change

SANs can use virtualization• Does “V” ensure integrity?

• Is “V” recoverable? (will it support serverless

backup?)

File system data structures must be

included for non-stop scalability!Secret

StoringStoring

StoringStoring

FilingFiling

The Fine Print in Scalability

How does the filing function

know about the new

storing address

space?

Evolving Architectures

Evolving Storage Network Architectures

Filing technologies are intimately involved

with:• Integrity

• Recoverability

• Security

• Availability (sharing)

• Scalability

• Performance (efficiency - working smart)

Hmmmmm? Maybe filing could be important!

Good Idea

DAFS

Network Appliance (and others?)

Puts rigor into NAS wiring

Important proof of concept for NAS• Eliminate doubts about NAS for database I/O

Relocating Filing Functions in the Storage Network

Systems need to have a data view• Can be achieved by aggregating views from

distributed

Metadata is moved out of host systems• Distributed or network-central

Data structures can be managed by the

subsystem• Enables subsystem-based recoverability

• Delivers enormous scalability

Aggregating Data Views

Virtualization at the file level

Data views from many subsystems are merged

Independence of Metadata from Hosts

Integrity (locking)

Scalability

Metadata

Systems

Storage

12

3

Independence of Metadata from Hosts

Systems

Storage

Distributed Metadata

Subsystem-Managed Data Structures

Systemwithout data structure function

Data structure is distributed across multiple subsystems