What is disk journaling, exactly?

[adambyte]

When snooping around Panther's Disk Utility, I noticed that my disk format is now HFS+ with Journaling. Also, there's a button do enable or disable it on other disks... exactly what does journaling do? Do other disk formats/ operating systems have this? Would I want to turn this feature on with my iPod?

So, yiis. What is it?

 

[mr. k]

Basically a log of all the data that is written to your hard drive, because say your mac crashes (what is a crash, anyway?) and a certain file is damaged on the harddisk, instead of running a full blown fsck, the journal of your disk shows any data that was corrupted and allows it to be fixed rather quickly.
http://en.wikipedia.org/wiki/Journaling_filesystem
http://www.afp548.com/Articles/Jaguar/journaling.html
^ some more info.