Operating Systems - Quick Questions -- 2

Please provide written responses to the following questions. Each response should be about a paragraph or two in length. Describe the following types of directory structures for a filesystem, including listing pros and cons of each type: Tree-Structured, Acyclic Graph-Based, and General Graph-Based. Describe what an inode is on a UNIX filesystem. Give several examples of pieces of data that would be stored in an inode. Describe the process for doing an I/O over DMA in a modern system. Be sure to include how interrupts are used in the process. Consider the following snapshot of a system's resource allocations: Allocation Max Available A B C D A B C D A B C D P0 0 0 1 2 0 0 1 2 1 5 2 0 P1 1 0 0 0 1 7 5 0 P2 1 3 5 4 2 3 5 6 P3 0 6 3 2 0 6 5 2 P4 0 0 1 4 0 6 5 6 Is the system as described in a safe state? If so, give an order that the processes could complete successfully. If not, describe why the system is not in a safe state. If a request from P1 for (0, 4, 2, 0) comes in, can it be granted immediately? Show why or why not. (Question adapted from OSC 9e.) Describe how the LRU algorithm for virtual memory page replacement works. Describe at least one way that LRU can be approximated with simpler hardware than a full implementation would require. Task should be completed within 2 or 3 hours.