# become root
# or
sudo bash;

lsblk; # list block devices, checkout what harddisks are there
sda      8:0    0 47.7G  0 disk
└─sda1   8:1    0 23.9G  0 part /
sr0     11:0    1 1024M  0 rom

# i assume the new partition will be created on the first harddisk

fdisk /dev/sda; # open up the first hd for creating a new partition
n; # new partition
p; # primary
Partition number (2,3, default 2); # just hit enter here to go with the default;
w; # write changes to disk and exit

The partition table has been altered.
Calling ioctl() to re-read partition table.
Re-reading the partition table failed.: Device or resource busy

# Device or resource busy -> note: you might need to reboot now to make the changes effective (inform kernel)

reboot; # reboot system
lsblk; # checkout what is there

sda      8:0    0 47.7G  0 disk
├─sda1   8:1    0 23.9G  0 part /
└─sda2   8:2    0 23.9G  0 part  <- this is new
sr0     11:0    1 1024M  0 rom  

mkfs.ext3 /dev/sda2; # format the partition with ext3
e2label /dev/sda2 "DATA"; # label the partition DATA

mkdir /mnt/sda2; # create mountpoint

vim /etc/fstab; # open fstab config file for automounting the partition

# at the end of the file add the following line
/dev/sda2 /mnt/sda2 ext3 relatime,errors=remount-ro 0 1

# mount options explained:

# relatime
## A filesystem mount with this option causes the access time to be updated if they are (before the update has occurred) earlier than the modification time.
## This significantly cuts down the writes caused by atime updates.
## However not many people use this option because they are simply not aware of it.
## relatime is a good compromise between atime (most expensive) and noatime (least expensive).

# errors=remount-ro
## will mount the filesystem in read-only mode in case there are any problems with it. This prevents you from potentially losing data using a bad filesystem.
## If this happened to one of your partitions, you should probably boot from a livecd or floppy (if it's not on your root partition, you can boot on recovery mode) and then run fsck on the affected disk.

:wq; # save and quit vim

reboot; # reboot again

mount; # checkout mount points

mount|grep sda2; # checkout mount points of sda2
/dev/sda2 on /mnt/sda2 type ext3 (rw,relatime,errors=remount-ro,data=ordered)

# sda2 was correctly and on-boot mounted to /mnt/sda2

cd /mnt/sda2; # go there
touch 1 2 3; # make some changes;
rm 1 2 3; # works