cat /dev/zero > /dev/device is the fastest way bar none for the spinning rust.
If you have an SSD drive, blkdiscard /dev/device is even faster. It will not physically write zeros but it will effectively wipe the data (so you'll get zeros if you try to read it).
dd if=/dev/zero of=/dev/sdX bs=1M
dd copies bits from "if" to "of". Blocksize 1M is usually a good value for performance. Repace sdX with your acual drive.
If you need to see a pgrogress, install "pv" (pipeviewer)
pv /dev/zero > /dev/sdX
You can use shred:
shred (from the coreutils package) is a Unix command that can be used
to securely delete individual files or full devices so that they can
be recovered only with great difficulty with specialised hardware, if
at all. By default shred uses three passes, writing pseudo-random data
to the device during each pass. This can be reduced or ...
From the e2fsck man page (e2fsck is also linked to names fsck.ext2, fsck.ext3 and fsck.ext4):
Note that in general it is not safe to run e2fsck on mounted filesystems. The only exception is if the -n option is specified, and -c, -l, or -L options are not specified. However, even if it is safe to do so, the results printed by e2fsck are not valid if the ...
If your going to be using Steam to install your games you can select where the games library is stored. And if your going to use wine to install WOW wine uses a folder in your home directory to store games so either way you should be good.
Hope this helps,
hdparm does not have the ability to find the write speed. According to the information under how to test the read and write speeds of a hard disk in linux, you can time a call to dd, or use the tools Bonnie++ and piozone.
I found your question when researching why my supposedly "new" drive showed its last self test at about 5.7 years powered on:
SMART Self-test log structure revision number 1
Num Test_Description Status Remaining LifeTime(hours) LBA_of_first_error
# 1 Short offline Completed without error 00% 47986 -