It shouldn't get copied, but simply is mounted into the local file system. the issue you may have is that you do not unmount after logoff.
So check this out:
<pam_mount>
<debug enable="0" />
<volume
fstype="cifs"
server="{server}"
path="%(USER)"
mountpoint="/home/local/{domain}/%(USER)"
user="*"
options="sec=krb5,cruid=%(USERUID),domain={full domain},uid=%(USERUID),gid=%(USERGID),rw"
/>
<umount>umount -l %(MNTPT)</umount>
<mntoptions allow="nosuid,nodev,loop,encryption,fsck,nonempty,allow_root,allow_other" />
<mntoptions require="nosuid,nodev" />
<logout wait="0" hup="0" term="0" kill="0" />
<mkmountpoint enable="1" remove="true" />
</pam_mount>
(replace {server}, {domain} and {full domain} with your individual real entries)
Works for me, however, from time to time, the very first login may fail to mount the home directory. Leaves you with a fresh desktop. Logo and login will then mount correctly. Not sure where this comes from, though.
Maybe also another tip:
If you want to keep the audio working, you also need to set a local variable for each client.
It must be done for each user, so it makes sense to put this as a template to the zentyal/samba server into /etc/skel/.profile
# move pulse directory out of home
PULSE_DIR="/tmp/$( whoami )-pulse
mkdir -p $PULSE_DIR && chmod 700 $PULSE_DIR
export PULSE_CONFIG_PATH=$PULSE_DIR
export PULSE_STATE_PATH=$PULSE_DIR
export PULSE_RUNTIME_PATH=$PULSE_DIR
Found this tip somewhere, but sadly do not remember the exact source, so credits go to the unknown hero
When a new user is created, the files in skel are copied to the new profile and when it's mounted by the client, you have full functional pulse audio.