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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