Update subversion from 1.5 to 1.6 on Centos 5.x

Stop service
# service svnserve stop

Update subversion using yum
# yum update subversion

Check the configuration svnserve daemon (/home/svn - repo home)
# cat /etc/sysconfig/svnserve
OPTIONS="-r /home/svn"

Upgrade svn repo
# svnadmin upgrade /home/svn/rep

Stat svnserve
# service svnserve start

You can compact repo to reduce the size
# svnadmin pack /home/svn/rep