I didn't want to start a new thread here, so I posted this here, I hope it's all right.

I decided not to make my own archive format, I want to create my own virtual file system instead. I've been doing some serious thinking recently, reading up on various file systems and I have two questions, I hope you can give me in-depth answers.

1.) What's journaling? I read it's used to monitor changes of disk's structure. But how does it really work? This data is stored on HDD or in memory?
2.) Do files on HDD using NTFS get fragmented? How does the deletion work in NTFS?