1. Content Addressed Storage
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Content Addressed Storage
Chapter 9
ISMDR:BEIT:VIII:chap5.5:CAS: Madhu N PIIT

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Chapter Objective
Upon completion of this chapter, you will be able to:
Describe CAS, fixed content and archives, traditional storage solutions for archive
Describe the features and benefits of a CAS based storage strategy
List the physical and logical elements of CAS
Describe the storage and retrieval process for CAS data objects
Describe the best suited operational environments for CAS solutions
ISMDR:BEIT:VIII:chap5.5:CAS: Madhu N PIIT

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Lesson: CAS Overview
Upon completion of this lesson, you be able to:
Define fixed content
Describe traditional archival solutions and its shortcoming
Define Content Addressed Storage (CAS)
List benefits of CAS
ISMDR:BEIT:VIII:chap5.5:CAS: Madhu N PIIT

4. What are Fixed Content and Archives
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What are Fixed Content and Archives
Generate
New Revenues
Improve
Service Levels
Leverage
Historical Value
Digital Assets Retained For Active Reference And Value
Electronic Documents
Contracts, claims, etc.
and attachments
Financial spread sheets
CAD/CAM designs
Presentations
Digital Records
Documents
Checks, securities trades
Historical preservation
Photographs
Personal / professional
Surveys
Seismic, astronomic, geographic
Rich Media
Medical
X-rays, MRIs, CTI
Video
News / media, movies
Security surveillance
Audio
Voic
Radio
ISMDR:BEIT:VIII:chap5.5:CAS: Madhu N PIIT

5. Challenges of Storing Fixed Content
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Challenges of Storing Fixed Content
Fixed content is growing at more than 90% annually
Significant amount of newly created information falls into this category
New regulations require retention and data protection
Often, long-term preservation is required (years-decades)
Simultaneous multi-user online access is preferable to offline storage
Need faster access to fixed content
Need for location independent data, enabling technology refresh and migration
Traditional storage methods are inadequate
ISMDR:BEIT:VIII:chap5.5:CAS: Madhu N PIIT

6. Traditional storage solutions for Archive
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Traditional storage solutions for Archive
Three categories of archival solution are:
Online, nearline, and offline based on the means of access
Traditional archival solution were offline
Traditional archival process used optical disks and tapes as media for archival
An archive is often stored on a Write Once Read Many (WORM) device, such as a CD-ROM
ISMDR:BEIT:VIII:chap5.5:CAS: Madhu N PIIT

7. Shortcomings of Traditional Archiving Solutions
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Shortcomings of Traditional Archiving Solutions
Tape is slow, and standards are always changing
Optical is expensive, and requires vast amounts of media
Recovering files from tape and optical is often time consuming
Data on tape and optical is subject to media degradation
Both solution require sophisticated media management
CAS has emerged as an alternative to traditional
archiving solutions
ISMDR:BEIT:VIII:chap5.5:CAS: Madhu N PIIT

8. What is Content Addressed Storage (CAS)
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What is Content Addressed Storage (CAS)
Object-oriented, location-independent approach to data storage
Repository for the “Objects”
Access mechanism to interface with repository
Globally unique identifiers provide access to objects
ISMDR:BEIT:VIII:chap5.5:CAS: Madhu N PIIT

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Benefits of CAS
Content authenticity
Content integrity
Location independence
Single-instance storage (SiS)
Retention enforcement
Record-level protection and disposition
Technology independence
Fast record retrieval
ISMDR:BEIT:VIII:chap5.5:CAS: Madhu N PIIT

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Benefits of CAS
Content authenticity
Content integrity
Location independence
Single-instance storage (SiS)
Retention enforcement
Record-level protection and disposition
Technology independence
Fast record retrieval
ISMDR:BEIT:VIII:chap5.5:CAS: Madhu N PIIT

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Lesson Summary
Key points covered in this lesson:
CAS Definition
Challenges of Storing Fixed Content
Shortcomings of Traditional Archiving Solutions
Benefits of CAS
ISMDR:BEIT:VIII:chap5.5:CAS: Madhu N PIIT

12. Lesson: CAS Architecture
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Lesson: CAS Architecture
Upon completion of this lesson, you will be able to:
Describe CAS architecture
Describe Physical and logical elements of CAS
Describe data storage and retrieval process in CAS environment
CAS examples
ISMDR:BEIT:VIII:chap5.5:CAS: Madhu N PIIT

13. Physical Elements of CAS
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Physical Elements of CAS
Storage devices (CAS Based)
Storage node
Access node
Servers (to which storage devices get connected)
Client
Storage Nodes
Private LAN
Access Nodes IP
API
CAS System
ISMDR:BEIT:VIII:chap5.5:CAS: Madhu N PIIT
Server

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CAS Terminology
API
Application Programming Interface (API)
A set of function calls that enables communication between applications or between an application and an operating system
Binary Large Object (BLOB)
The Distinct Bit Sequence (DBS) of user data represents the actual content of a file and is independent of the filename and physical location
ISMDR:BEIT:VIII:chap5.5:CAS: Madhu N PIIT

15. CAS Terminology (Cont.)
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CAS Terminology (Cont.)
C-Clip
A package containing the user's data and associated metadata
C-Clip ID (C-Clip handle or C-Clip reference) is the CA that the system returns to the client application
Content Address (CA)
An identifier that uniquely addresses the content of a file and not its location. Unlike location-based addresses, content addresses are inherently stable and, once calculated, they never change and always refer to the same content
C-Clip Descriptor File (CDF)
The additional XML file that the system creates when making a C-Clip. This file includes the content addresses for all referenced BLOBs and associated metadata
ISMDR:BEIT:VIII:chap5.5:CAS: Madhu N PIIT

16. How CAS Stores a Data Object
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How CAS Stores a Data Object
Client presents data to API to be archived
Unique Content Address is calculated
Object is sent
to Centera via Centera API over IP
CAS System
Application Server
API
Client
C-Clip
(Object)
CDF
ISMDR:BEIT:VIII:chap5.5:CAS: Madhu N PIIT

17. How CAS Stores a Data Object
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How CAS Stores a Data Object
Client presents data to API to be archived
Unique Content Address is calculated
Object is sent
to Centera via Centera API over IP
CAS System
Application Server
API
Object
Client
Acknowledgement returned to application
Clip ID is retained and stored for future use
Centera validates the Content Address and stores the object
ISMDR:BEIT:VIII:chap5.5:CAS: Madhu N PIIT

18. How CAS Retrieves a Data Object
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How CAS Retrieves a Data Object
CAS authenticates the request and delivers the object 4
Object is needed by an application 1
CAS System
Application Server
API
Client
Retrieval request is sent to the CAS via CAS API over IP 3
Application finds Content Address of object to be retrieved 2
C-Clip ID
ISMDR:BEIT:VIII:chap5.5:CAS: Madhu N PIIT

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CAS Features
Features available with most CAS systems are:
Integrity checking
Data protection
Local replication
Remote replication
Load balancing
Scalability
Self-diagnosis and repair
Report generation and event notification
Fault tolerance
Audit trails
ISMDR:BEIT:VIII:chap5.5:CAS: Madhu N PIIT

20. Example 1: CAS Healthcare Solution
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Example 1: CAS Healthcare Solution
Hospital
Application Server
API
Stored locally for
Data Stored
Short-Term Use
on CAS
Patient Studies
(60 Days)
CAS System
Each X-ray image ranges from about 15MB to over 1GB
Patient record is stored online for a period of days
Beyond 90 days patient records are archived
ISMDR:BEIT:VIII:chap5.5:CAS: Madhu N PIIT

21. Example 2: CAS Financial Solution
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Example 2: CAS Financial Solution
Bank
Application Server
API
CAS System
Check image size is about 25KB
Check imaging service provider may process 50–90 million check images per month
Checks are stored online for a period of 60 days
Beyond 60 days data is archived
ISMDR:BEIT:VIII:chap5.5:CAS: Madhu N PIIT

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Lesson Summary
Key points covered in this lesson:
CAS architecture
Physical and logical elements of CAS
CAS storage and retrieval process
CAS solution examples
ISMDR:BEIT:VIII:chap5.5:CAS: Madhu N PIIT

23. Copyright © 2009 EMC Corporation. Do not Copy - All Rights Reserved.
Chapter Summary
Key points covered in this chapter:
Benefits of CAS based storage strategy
Overview of physical and logical elements of CAS
Storing and retrieving data from CAS
CAS application examples
ISMDR:BEIT:VIII:chap5.5:CAS: Madhu N PIIT

24. Concept in Practice – EMC Centera
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Concept in Practice – EMC Centera
Centera Architecture
Based on RAIN (Redundant Array of Independent Node)
Access Node
Storage Node
Content
Mirrored Content
To Server
Storage
Nodes 1 2 3 4 5 6 4
Ethernet
LAN
Switch 3
Access/Storage
Nodes 6
Private 1
LAN 5 2
Ethernet
Switch
ISMDR:BEIT:VIII:chap5.5:CAS: Madhu N PIIT
Power Rails