Here is how to mount a windows/samba share permanently with your /etc/fstab:

First install the cifs-utils package:

# apt-get install cifs-utils

now create a credential file containing your user and password

# vim /home/myuser/.smbcredentials

add following lines:

username=myuser
password=mypassword
domain=mydomain (optional)

then secure its permissions:

# chmod 600 /home/myuser/.smbcredentials

after that open your /etc/fstab and add following line to it:

//servername/share /mymountpoint cifs vers=3.0,sec=ntlmssp,credentials=/home/myuser/.smbcredentials,iocharset=utf8 0 0

as a final step run

# sudo mount -a

Some explanations on the fstab line:

vers: this specifies the SMB protocol version, in my case version 3.0
sec: sets the security for the password hashes, here NTLMv2 password hash inside raw NTLM
credentials: sets the file with your credentials
iocharst: sets the encoding to UTF-8

(refer to man mount.cifs for parameter details)

I am using KVM on CentOS 6 (host) and FreeBSD 10.3 as a guest system. FreeBSD's hard disk write performance was horrible! It was about 2-5 MB/s! After searching some time, here the fix which led the write speed to 40 MB/s!

Open your VM config file with

# virsh edit <SERVER>

then find your hard disk config line and change the cache and io paramter accordingly. Here the wonderful line which gave it a awesome performance boost:

<disk type='file' device='disk'>
    ...
    <driver name='qemu' type='raw' cache='none' io='native'/>
    ...
</disk>

Save your config file and reboot your FreeBSD guest, you will see the difference is huge (at least in my case)