CST334 - Week 30

This week we focused on the topic of the persistence of data, the permanent storage of information. First, we learned about I/O devices and DMA - Direct Management Access, which limits overhead by transferring between devices and main memory with little CPU intervention, as opposed to programmed I/O (PIO) where the CPU transfers data to and from devices. Then we read about hard disk drives and their different parts including the platters, spindle, and read/write head which senses and changes the magnetic patter present on the different tracks on the disk to read/write. Disks must schedule I/O requests and keep in mind the seek, rotation, and transfer times. RAIDs allow for larger, faster, and more reliable disks by using multiple disks together, aiding in performance, capacity, and reliability with the redundancy of data.

The next things we focused on were files and directories. The textbook discussed all the details of creating, reading, and removing files and making and deleting directories. We also delved into the details of hard and soft links. Then we learned about the organization of file systems and about the superblock, which stores important information that the file system needs. A bitmap is used to keep track of which blocks are free and which are in use. We learned about the inode structure and the complexities of the file system. There was a lot to cover this week and now I have to study and prepare for the final exam!