Transcript Agenda
Agenda • Data Storage • Database Management Systems • Chapter 3 • AOL Time-Warner Case Data Storage • • • • • • • Character Sets File Systems RAID File Storage Network File Systems Internet File Systems 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 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 Shared Storage Arrays Vendors: StorTek, IBM, EMC, … Goals: Management, flexibility Issues: Connectivity Virtual Storage 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 B Disk A Block 1 RAID 5 Diagram (Even Parity) Disk A Disk B Disk C Disk D Parity Disk 1 0 0 1 0 Storage Mechanism Remote Data Network File Systems Internet File Systems Considerations: Performance Security “Roaming” Storage Area Networks “Fabric” connectivity between servers and storage Access is still via “owning” server Used for structured data, data associated with specific application “Fabric” Storage Area Network Disk A Disk B SAN Side 1 Server 1 Server 2 Disk C Disk D Disk E SAN Side 2 Server 3 Server 4 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 NAS Network Server Server 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 Relational DBMS Concepts • Value-based relations • Joins • Tables and Views • Set Processing 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 Text Chapter 3: Discussion • What systems enable “companysmart” decisions • When does “scope of control” effect growing firms Case: AOL Time Warner • Is the company successful? • Explain stock drop vs other Internet “servicers” • What (if any) “rules” were broken?