Operating Systems 2014F Lecture 14

How does an operating system know it's accessed memory it doesn't have access to? A lot of you said segments.

Filesystems - normally operating system mechanisms are

talking about access to hardware systems, persistent storage. - abstraction for persistent storage. Storage that maintains it's state when it loses power. A couple of challenges with persistent storage. What's weird about storing things in persistent storage? It's slow. durability and persistent.

Going to make errors - we should be able to recover from them. Maybe not fix everything, but preserve most of the data. This is a huge burden on filesystems. Filesystem development tends to be very slow in practice. Whatever code you have doing this, has to do this right. Older filesystems tend to be more trustworthy, when hardware changes, bugs you didn't know where in the filesystem may come up.

what do we have today? Indexed filesystems.

There is typically a minimum storage allocation given to every file. That's the minimum size of a file, it's taking up 4 k / 8 k. this is not strictly true for all file systems. There was a filesystem that allowed arbitrarily sized files. (ReiserFS)

Unifying a keyvalue store for smaller and larger filesystems wasn't considered a priority.

Make filesystems do, on modern filesystem, rather than trying to optimize the storage of small files. It's not so much filesize that is the issue.