hi
i need quick help my dear friends.

1- in BTRFS file system is there journaling??
i mean do BTRFS do journaling?

2-what is the differences between journaling and COW(copy on write)??????

I think maybe you should spend some time on the brtfs wiki.

1 members found this post helpful.

i've read that before. only in "log tree" part it said a little about cow.
so if u can't help more don't reply like this.

http://en.wikipedia.org/wiki/Comparison_of_file_systems

In a simple sense a journal is much like the word we use in writing. A daily journal would be a collection of notes of one's day. A file system journal is a collection of notes as to what operations were performed or in process. A journal could help the OS to recover what the state of files were in case some issue like power loss happened.

Copy on write is a sort of clone or full image of the file instead of a simple note as to what was done. This clone feature is sort of like a time machine or could be used as such to recover the changes made in some file. A text file that has been edited could have only the changed part saved in some area. If needed the file could be recovered to the original state by the saved image (parts of image even)

This is all very basic.