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Disks; Distributed Systems

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Presentation on theme: "Disks; Distributed Systems"— Presentation transcript:

1 Disks; Distributed Systems
Tanenbaum ch. 5.4 Distributed Systems Tanenbaum ch. 8.3

2 Disk Hardware Information written onto the disk in concentric circles
At any arm position,each head can read a track All the tracks for a given arm position forms a cylinder

3 Disk Parameters For the 20GB disk, 281 x 512=140KB/track
Transfer a track in 1 rotation time of 8.33ms or a transfer rate of 17 MB/sec 7200rpm

4 Disk Geometry Virtual Physical Divide the disk into zones with more sectors on the outer zones than the inner zones

5 Strips and Stripes

6 RAID Use parallel I/O to improve performance
Redundant Array of Inexpensive Disks Organized into 6 levels stripe

7 RAID Levels Level 3-5

8 Nested RAID Combine data redundancy and performance
of Raid 0 and Raid 1 Raid 1+0 is better for recovery

9 Comparisons of Multiple CPU Systems

10 Distributed Systems Multiple complete computers connected by a network
Example: our site: blade01, …, blade42, ulab,… are all separate computer systems, but networked together sharing a global distributed NFS file system login onto blade12, look at your login dir login onto ulab, see the same files Distributed system turns a loosely connected bunch of machines into a coherent system

11 Middleware

12 Networking Hardware

13 Networking Services

14 Network Protocols Protocol- the set of rules by which computers communicate Organize as a stack OSI Layer Example Kind of software (UNIX, Windows) Application Web server, browser User-level Transport TCP Kernel Network IP Kernel Data Link Ethernet Kernel Physical Cat5 cable, etc. Hardware

15 Interaction of Protocols


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