Chapter 9

Section 2 : Storage Networking Technologies and Virtualization

Content Addressed Storage (CAS): features and Benefits of a CAS

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

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

Electronic Documents•Contracts, claims, etc.

•E-mail and attachments

•Financial spread sheets

•CAD/CAM designs

•Presentations

Digital Records•Documents

– Checks, securities trades– Historical preservation

•Photographs– Personal / professional

•Surveys – Seismic, astronomic,

geographic

Digital Assets Retained For Active Reference And ValueDigital Assets Retained For Active Reference And Value

Leverage Historical Value

Improve Service Levels

Generate New Revenues

Rich Media•Medical

– X-rays, MRIs, CTI

•Video– News / media, movies– Security surveillance

•Audio– Voicemail– Radio

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

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

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

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

Content authenticity Content integrity Location independence Single-instance storage (SiS) Retention enforcement Record-level protection and disposition Technology independence Fast record retrieval

Additional Task

Research on role of CAS in ILM Strategy

Key points covered in this lesson: CAS Definition Challenges of Storing Fixed Content Shortcomings of Traditional Archiving

Solutions Benefits of CAS

CAS Architecture, Storage and Retrieval, Examples.

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

Storage devices (CAS Based)◦ Storage node◦ Access node

Servers (to which storage devices get connected)

Client

Server

Private LAN

Storage Nodes

Access Nodes

CAS System

IP

API

Application Programming Interface (API)◦ A set of function calls that enables

communication between applications or between an application and an operating system

BLOB (Binary Large Object) ◦ The actual data without the descriptive

information (metadata)◦ The Distinct Bit Sequence (DBS) of user

data represents the actual content of a file and is independent of the filename and physical location

API

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

API

Unique Content Address is calculated

Client presents data to API to be archived CAS System

Client

Application Server

CDF

C-Clip(Object)

Object is sent to CAS System via

CAS API over IP

API

Unique Content Address is calculated

Client presents data to API to be archived CAS System

Client

Application Server Object is sent to CAS System via

CAS API over IP Object

CAS System validates the Content Address and stores the object

Acknowledgement returned to application

Clip ID is retained and stored for future use

Application Server

Client

CAS System

Object is needed byan application

1 CAS authenticatesthe request and

delivers the object

4

Application findsContent Address of

object to be retrieved

2 Retrieval request issent to the CAS System via

CAS API over IP

3

API

C-Clip ID

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

Through the use of redundant components and data protection schemes

◦ Audit trails Documentation of management activities, access and

disposition of data

Each X-ray image ranges from about 15MB to over 1GB

Patient record is stored online for a period of 60-90 days

Beyond 90 days patient records are archived

Data Stored on CAS

Patient Studies

Stored locally for Short-Term Use

(60 Days)

Hospital

CAS SystemApplication Server

API

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

Bank

CAS SystemApplication Server

API

Key points covered in this lesson: CAS architecture Physical and logical elements of CAS CAS storage and retrieval process CAS solution examples

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