maven3 local repository settings

The default local repository of maven, by default, whether on windows or linux, each user has a repository directory with a path named .m2/repository/ in his own user directory. Because the C drive space is not enough, consider customizing the local warehouse directory address.
M2_REPO is set in windows and found to have no effect.
I had to create the content of ~/.m2/settings.xml
as
<settings> 
    <localRepository>D:\m3\repository\</localRepository> 
</settings> 

go to: http://blog.chinaunix.net/uid-192452-id -3552400.html