1. Agenda Data Storage Database Management Systems Chapter 3 AOL Time-Warner Case

2. Data Storage Character Sets File Systems RAID File Storage Network File Systems Internet File Systems Storage Area Networks Network Attached Storage

3. Character Sets Representations of all text elements ASCII – Standard for PC’s, unix EBCDIC – The Mainframe alternative UNICODE – The web standard

4. File System Concepts and Issues File Allocation Table (FAT) / Volume Table of Contents (VTOC) Disk Sectors and Fragmentation Hierarchical File Systems Journaled vs raw file systems Disk Caching Mechanism Reason

5. Shared Storage Arrays Vendors: StorTek, IBM, EMC, … Goals: Management, flexibility Issues: Connectivity Virtual Storage

6. 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

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

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

9. RAID 5 Diagram (Even Parity) Disk A Storage Mechanism Disk B Disk C Disk D Parity Disk 1 0 0 1 0

10. Remote Data Network File Systems Internet File Systems Considerations: Performance Security “Roaming”

11. Storage Area Networks “Fabric” connectivity between servers and storage Access is still via “owning” server Used for structured data, data associated with specific application

12. “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

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

14. NAS Diagram Network Server NAS

15. Database Management Systems Programs that manage databases Link different data structures logically Single version of all rules –Structures –Domains –Access Data reliability enhancements –Locking –Logging –Journaling Standard “API” –SQL: Structured Query Language Granular Access

16. Relational DBMS Concepts Value-based relations Joins Tables and Views Set Processing

17. Text Chapter 3: Themes Networking the Business –“Act big and small” –“Fast firms” Blueprint –Operating Processes –Managing and learning Value Networks –Virtual Integration –Cost/Risk Analysis –Market Relationships –Proprietary processes vs Virtual Integration

18. Text Chapter 3: Discussion What systems enable “company- smart” decisions When does “scope of control” effect growing firms

19. Case: AOL Time Warner Is the company successful? Explain stock drop vs other Internet “servicers” What (if any) “rules” were broken?