Is there a good practice to make a branch of a subdirectory of "trunk" ?

Question

I have a project, that contains many parts. I'm going to make a branch for only a subpart of the project, rather the entire project.

Is there a good practice to do so ?

Or, i should branch the entire "trunk", to avoid some problems ?

The only problem, i see, is a confusion about - what part of the project was actually branched. Because svn lazy copies only content of the folder, being branched

Answer 1

i would go for branch of whole trunk, its not expensive.

Answer 2

Following svn standards, you can make branch only from tag or trunk. So, the following are good practice:

 svn copy project/trunk project/branches/<branch_name>

or

 svn copy project/tags/<some_tag> project/branches/<branch_name>

You wouldn't bother about extra space on server in this case since these are "virtual" copies, svn server operates with real differences between revisions.