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OSD TWG

Mike Mesnier

January 2003

Object-based Storage 101

SN

IA

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OSD TWG

Storage Trends/Facts• Storage is moving to the network

– Servers connect to consolidated NAS or SAN storage

• Storage and networking fabrics are converging– iSCSI, iFCP, RDMA/TCP, …

• Storage is becoming more autonomous– Standards for richer interfaces and protocols

– More functionality in the storage device

– Research focusing on intelligent storage• Self-aware, self-managing, self-configuring

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SwitchedSwitchedFabricFabric

Compute and storage Compute and storage platforms are tailored platforms are tailored for specific functions.for specific functions.

DB Servers

File Servers

Web Servers

Load Balancers

SAN Storage

Building Blocks

Storage Bricks

Compute Bricks

Tonight’s Talk

Evolving Data Center

Fire Walls

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• Imagine a storage brick that is:– Always available and reliable– Self-securing– Self-managed– Infinitely scalable (i.e., stackable)

Object-based storage is a step closer…

Storage Utopia

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Storage today

• Emerging solutions

• Object-based storage

• SNIA activity

Agenda

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Storage App.

HOST

…

Direct Attached Storage

CLIENT CLIENT

Network

…File System

Network Attached Storage

Storage App

HOSTStorage App

HOST

Network

…

Storage Area Network

How did these evolve?

Local Storage Shared Data Shared Capacity

Architectures Today

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• DAS – physically secure and simple– Not scalable– Limited connectivity for capacity sharing – No data sharing

• SAN – scalable capacity sharing– Limited (coarse) security through switch– No data sharing

• NAS – secure sharing (data or capacity)– Limited scalability

The Trade-offs

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• DAS and SAN provide raw block storage– No model for the stored data (e.g., files)– No support for data sharing (e.g., concurrency control)

• Storage applications built using DAS or SAN– File systems, databases, video servers, etc.– App. implements a data model (e.g., a file)– May implement direct data sharing (e.g., via clustering)

• NAS is an application for indirectly sharing data– Servers export local file systems over the network– Clients share data by sharing files

The Usage Models

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• Data centers need to share data.– Backup, HSM– Clustering for scalability (e.g., file server and db)

• Sharing data directly on the SAN is difficult.– Concurrency control, lock management, versioning– Distributed security

• Sharing data through NAS is easy– But imposes limits in scalability

• Single point of failure & bottleneck

Challenge: Data Sharing

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• Storage todayEmerging solutions

• Object-based storage

• SNIA activity

Agenda

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• Virtualization (NAS & SAN)– Aggregates heterogeneous NAS and SAN devices

• Clustering the file system– Mitigates file server bottleneck

• Giving clients direct access to storage devices– File servers share block metadata with clients– Eliminates file server bottleneck

• Changing the device interface – From blocks to objects

Emerging Solutions

NAS ClientsNAS Clientse.g. Web e.g. Web serversservers

SAN Islands

NAS Islands

SAN Virtualization

NASVirtualization

Clients need direct access to remove bottleneck.

Network

FILES

+ Clustering

BLOCKS

1st Generation File Server

OSD TWG

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ServersServers

Block-Based StorageBlock-Based Storage

MANAGEMENT

Eth switchTrusted SAN

DA

TA

ClientsClients

METADATA

Must be trusted

Difficult to directly share

2nd Generation File Server

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• Storage today

• Problems and partial solutions Object-based storage

• SNIA activity

Agenda

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ID x123Blocks:3,42Length:512

Objects can be self-describing!

• An object comprises– Application data (e.g., file, record)– Device-managed metadata (e.g., block allocation)– User-accessible attributes (e.g., access times)

• Objects have file-like methods for access– Open, close, read, write, get/set attributes– Commands are authorized

• Object-based storage devices– Disk drive, appliance, controllers

Object Storage

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Object Storage Model

Block Interface

Storage Device

Block I/O Manager

Object Interface

Applications

File SystemUser Component

File SystemStorage Component

System Call Interface

CPU

Applications

File SystemUser Component

System Call Interface

CPU

Storage Device

Block I/O Manager

File SystemStorage Component

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So What’s the Real Value of Objects?

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The Value of Objects

• Better security via capabilities– Each object can have its own security domain– All I/O is authorized by the device

• Easier to share data– Files and records can be stored as objects– Low-level metadata managed by device

• Opportunities for intelligence– Attribute-based learning for resource allocation

• Better caching, pre-fetching and staging of data– Self-configuring storage w/ continuous reorganization

• Layout objects to best serve client requests

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• Separates policy from enforcement– Storage managers set policy– Storage devices enforce the policy

• Prevents unauthorized access

• Minimizes interaction with storage manager

• Minimizes state kept on device– For better scalability, recovery and cost

Value #1: Security

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Security Types

• Types of security– Authentication – “you are who you say”– Authorization – “you have permission”– Integrity – “data is not corrupted/modified”– Privacy – “data is not seen”

• TWG is considering two scenarios– Channel is trusted– Channel is not trusted

OSD handles all but authentication.

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Preventable Attacks

• Snooping or modification of commands and data• Unauthorized access via modified capability• Delay and replay attacks• Guards against these attacks, respectively:

– Transport or app-level encryption for privacy– Transport or app-level digests for integrity– Cryptographically secure capability– Nonce (timestamp) attached to each command

• Requires loosely synchronized clocks• Only needed when channel is not trusted

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• Less metadata to keep coherent– No block allocation or free block lists

– Shorter “lists” to manage• Objects may contain aggregation metadata

– Leads to better scalability

• Backup and HSM– No need to co-locate w/ application (e.g., file system)

– Only backup necessary objects (not entire volume)

Value #2: Data Sharing

OSD is really a file system less the naming

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3rd Generation File Server

Managers

Object-based Storage Devices

MANAGEMENTEth switchSAN

Clients

SECRETSECRETKEYKEY

SECRETSECRETKEYKEY

SECRETSECRETKEYKEY

Access Request

DA

TA

Intelligent Device

Space ManagementBackup/RecoveryQoS via attributesSecurity

Validate CapabilityValidate CapabilityValidate CapabilityValidate Capability

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• Objects can have rich attributes– Timestamps, accounting information, QoS parameters, group and

user information, client-specific usage patterns• Many opportunities for policy-based management

– E.g, attributes may describe backup and QoS policies• Attributes may also provide “information gain”

– An object’s actions may be correlated with its attributes• E.g., Any object written within the last 24 hours will be read up at 4

a.m. the following day (i.e., for backup)

• Can devices actually learn??– This is an active research topic– OSD facilitates a further investigation– Big questions: which attributes really matter?

Value #3: Intelligence

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• Storage today

• Emerging solutions

• Object-based storage SNIA activity

Agenda

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• Charter and Program of Work:– Requirements for OSD– Transport independent definition of OSD– SCSI Standard for OSD– White papers & industry demonstrations

• ~100 members and over 30 organizations – academia, industry, National Laboratories and

startups.

The SNIA TWG for OSD

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• Establishing the commands – v1 DONE• Establishing the attributes – v1 DONE• Security architecture – v1 DONE• How should we identify and locate objects?• How to maintain integrity through failures?• Should we support transactional semantics?• Management of hundreds or thousands of OSDs.

Work Items in the TWG

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OSD FunctionsSecurity

• Authorization• Integrity• Privacy

Attributes• Aid to file systems• Hints to device• QoS and Priorities• Logging & Statistics

Basic Protocol– Read

– Write

– Create

– Delete

– Open

– Close

– Get

– Set

– Append

– Clear

Basic I/O

Space Mgmt

Session “hints”

Attributes

Other cmds

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• A big challenge in the enterprise is data sharing– Must be secure and scalable

• Objects complement existing technologies– Add security, low-overhead data sharing and intelligence

– Enable the 3rd generation file server

• OSD is more active now than ever– SNIA has become the focal point

– Will complete v1 SCSI standard 1st half of this year.

Summary

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Call to Action

• How must your file system change to support OSD?• How will OSD change your backup story?• See the latest OSD standard at T10• Understand our plans for other transports• Get involved in the OSD TWG

– Architecture– Standards efforts– Industry demonstrations

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• Academic research– www.pdl.cmu.edu– www.dtc.umn.edu– csl.cse.ucsc.edu/obsd.shtml

• Standards work– www.snia.org/osd– www.nsic.org/nasd– www.t10.org/scsi-3.htm (see OSD)

• Industry research & development– www.intel.com/labs/storage/osd

• Download OSD Reference Code

– www.haifa.il.ibm.com/storage.html– www.lustre.org– www.panasas.com

Further References

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Our Leaders

• Mike Mesnier, Julian Satran (co-Chairs)

• Applications – Erik Riedel

• Education – Tom Ruwart

• Management – Ken Samarra

• Security – Michael Factor

Contact us to get involved!