Distrubuted file systems

Question 1

File

Answer 1

The components of a file include:
- Name (usually filename and extension)
- Content (a list of bytes)
- Type (regular, directory, etc)
- Attributes (owner, permissions, current size, creation time, etc. Basically metadata)

Question 2

Google File System (GFS)

Answer 2

“It’s a distrubuted file system that is optimised to deal with:
- Frequent component failures (e.g. bugs, servers, switches, etc)
- Multi-gigabyte files
- Append-mostly data
Also, it’s built with specific user applications in mind”

Question 3

Strict consistency

Answer 3

Says an update on the same piece of data stored in multiple areas at once (e.g. on the cloud) must be seen instantly by other data.

Question 4

Eventual consistency

Answer 4

Says an update on the same piece of data stored in multiple areas at once (e.g. on the cloud) doesn’t have to be immediately updated, and it’s allowed to take its time

Question 5

Contiguous Allocation

Answer 5

It’s basically like you’ve got a bookshelf with books. When you take out a book (delete a file), you’ve actually created a gap in the bookshelf where a book once stood. If you want to add a new book to the shelf, you’ll first of all go through all the gaps in the bookshelf and see whether there is a large enough space in the bookshelf in order to fit it in. If there is enough space, you put it in that space. If not, then you’ll have to add it onto the end.