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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