# disk-filltest - Simple Tool to Detect Bad Disks by Filling with Random Data #

The number of hard disk produced in the last five years is huge. Of course,
this is the same number of hard disks that will most probably fail in the next
five years, possibly with catastrophic consequences for the particular user or
business.

The simple tool disk-filltest can help, together with S.M.A.R.T. monitoring, to
check disks periodically and thus be forewarned about coming failures. The
function of disk-filltest is simple:

* Write files random-######## to the current directory until the disk is full.

* Read the files again and verify the pseudo-random sequence written.

* Any write or read error will be reported, either by the operating system or
  by checking the pseudo-random sequence.

* Optionally, delete the random files after a successful run.

The method is simple and effective, however, it of course does not verify other
files on the disk. That is a different task, which can be solved efficiently
using digup (a Digest Updating Tool) (https://panthema.net/2009/digup/).

Another useful side-function of disk-filltest is to measure read/write speed
while filling the disk. Slow speeds may also indicate a future failure, or just
bad disk controlling.

The program runs on Linux, Windows and probably any other POSIX-compatible
system. The whole source code is one .c-file.

See https://panthema.net/2013/disk-filltest/ for more information.

Written 2013-03-27 by Timo Bingmann <tb@panthema.net>