[CentOS] Utility to zero unused blocks on disk

On 02/08/2016 03:05 PM, m.roth at 5-cent.us wrote:
> Wes James wrote:
>> Is there a utility to zero unused blocks on a disk?
>>
>> CentOS 6.7/Ext4
>>
>> I saw zerofree, but I’m not sure it would work on Ext4 or even work on
>> this version of CentOS.
>>
> I don't understand the point of doing this.

Wes didn't say the reason he wanted to zero unused blocks, but I always 
do this in kickstart scripts when constructing VM images as the image 
size is considerably reduced by doing this...

-Greg