Class 3 Agenda  Review  Data Management  State St Bank Case  Text: Network Effect

Review  Network Concepts Take-aways  IP Address Shortage

Data Management Concepts  Representing Data  Character Sets  Binary formats  Structured/Non-structured data  File Systems  Storage Arrays and RAID  Server Mass Storage Mechanisms  Storage Area Networks  Network Attached Storage

Character Sets  Representations of all text elements  ASCII – Standard for PC’s, unix  EBCDIC – The Mainframe alternative  UNICODE – The web standard: many more characters

Ascii Character Set Example (with Parity) _ _ _ _ = a = A = 5

Structured vs Non-structured Files  Definition  Impact on Storage  Impact on Access  Self-defining records

File System Concepts and Issues  Storage: Blocks and Sectors  Writing and caching  Fragmentation and re-organization  Organization: File Hierarchies  Folders, directories and qualifiers  Inheriting and overriding properties  Shared File Systems  Client Sharing  File Servers

Shared Storage Arrays  Level of abstraction / Virtualization  Vendors: StorTek, IBM, EMC, HP, …  Goals: Management, flexibility  Issues: Connectivity, Security

Non-Storage Array Model svrA svrB svrC disk1 disk2 disk3

Storage Array Model svrA svrB svrC disk1 disk2 disk3 DISKADISKA

RAID (redundant array of independent disks)  RAID 0 (Striping)  Consecutive blocks written to different disks  Performance gain only  RAID 1 (Mirroring)  Writes all data to two separate drives  Reads from either for performance  RAID 5 (Parity disk)  Any disk can fail without loss  Parity drive allows failed drive to be recreated

 RAID 0 Diagram (Striping) Disk A Disk B Disk C Disk D Block 1 Block 2 Block 3 Block 4

RAID 1 Diagram (Mirroring) Disk A Disk B Block 1

RAID 5 Diagram (with even Parity) Disk A Disk B Disk C Disk D Parity Disk

Advanced Data Management  SYSTEM Managed Storage  Multiple levels of access  Automatic promotion/demotion  Catalog of “where”  Merging of “backup” copies  Master Data Management  On “Common functions” tier shared by business applications  Mechanism for sharing, requesting changes  Resolves duplicates, ownership, domains

Storage Area Networks  “Fabric” connectivity between servers and storage  Access is still via “owning” server  Used for structured data, data associated with specific application  Typically use specialized connections

“Fabric” Storage Area Network Server 1Server 2Server 3Server 4 SAN Side 1 SAN Side 2 Disk A Disk B Disk C Disk D Disk E

Network-Attached Storage  File systems accessed via internet  Appear as remote drives  Used for unstructured data (e.g. documents), data used by many servers

NAS Diagram Network Server NAS

State St. Bank: “A Higher Power” Distinguish “Governance” from “Management” Distinguish “Governance” from “Management” Governance is necessary in every aspect of business. Why is it singled out in IT/IS management? Governance is necessary in every aspect of business. Why is it singled out in IT/IS management? Why not take over and run the Deutsche Bank applications “as is”? Why not take over and run the Deutsche Bank applications “as is”? What information is needed for proper decisions on a client? Who is responsible for that information? What information is needed for proper decisions on a client? Who is responsible for that information? What type of planning and preparation enhance “nimbleness”? What type of planning and preparation enhance “nimbleness”?

 Homework  Mon: Text Chapter 4: Moore’s Law  Wed: Case Study: Netflix (Chapter 3 in Gallaugher)  Wed: Receive take home midterm exam (due next Monday)