NOTICE: As of March 3,
2005, Autoclave is no longer supported. Please see the End-Of-Life Notice for details and an alternative.
February 21, 2003
hard drive sterilization on a bootable floppy
Frequently Asked Questions
Please read this page carefully before mailing me for support.
Also, please check out the usage instructions.
Thanks. First,
a disclaimer: I don't use Windows much at all. Autoclave works by booting
your computer with a small Linux operating system. I developed it using Linux,
and I always use Linux when creating the bootable floppy. Rawrite was written
by someone else, and I don't know much about it. If your problem involves not
being able to create the bootable floppy, I might or might not be able to help.
That aside:
- What does Autoclave do?
It securely erases everything in the writable space on a hard drive.
Everything. All the files, all the free space, the partition table,
the boot sector, the works.
This includes the operating system and any preinstalled packages your
hardware vendor may have included on the drive when you got it. Everything.
I don't know how to say this more emphatically. When Autoclave is done
running, you will have a hard drive filled with zeros, and nothing else.
- Really? Everything?
Ok, that was a bit of a simplification. No, it doesn't erase every single
block on the hard drive, just the blocks which are accessible at the time
Autoclave is run. Why would a block not be accessible? The drive's firmware
keeps a list of blocks which have gone bad. This information is stored on the
disk, but in a way such that only the disk's firmware has access to it.
Autoclave can't do anything about those blocks. Once a block has gone bad, and
been added to the bad block list, the firmware in the drive acts as if that
block doesn't exist. Without vendor-specific commands to tell the firmware to
make those blocks visible again, Autoclave can't see them, and won't overwrite
them. The older a drive is, the more likely it is to have blocks which have
gone bad and been made invisible by the drive itself. There may be data in
these blocks which could be recovered, but not without a lot of effort. Again,
it's a question of how valuable the data on the drive is. It's also possible
that the drive is failing, and some blocks can't be written to, even though
they aren't in the bad block list. Autoclave will try to clean these, but it
may or may not be successful, depending on how badly damaged the drive is. On
the bright side, if you've got problems like this, you should probably just
throw the drive away (physically destroying it first) rather than cleaning it
and reusing it.
- Isn't that what fdisk and format do?
No. When you partition and format a drive, in general way less than 1% of the
blocks on the drive actually get modified. It's trivial to retrieve data from
a drive which has been formatted.
- Is there a SCSI version?
Not yet, sorry. I have received a contribution of some code which will help
with making a SCSI version, but I still need a way for users to speicify which
kind of SCSI hardware they're using, as some SCSI drivers don't play well with
others. I am working on it, though, and the next version should definitely
have SCSI support.
- If I have more than one drive, can I use Autoclave to just erase one of them?
Yes. Please read the usage instructions. While the
example shown only has one hard drive, and shows you choosing from drive 1-1,
if there were four drives in the system, it would let you pick from drive 1-4.
- Can it be used to erase just a parition on a drive?
Not in this version. It works on the whole hard drive, ignoring partitions. In
fact, when it's done, there won't be any partitions on the drive at all. A
later version of Autoclave will probably support per-partition erasure.
- Once I've run Autoclave, can I reuse the drive?
Yes. If the drive was usable before you ran Autoclave, it should be usable
after. It won't have a partition table, so you can't just format it. You will
have to use "fdisk" or another partitioning tool to create a new partition
table, then format it. If you have problems reusing a drive after Autoclave
has cleaned it, please let me know.
- Will downloading Autoclave erase the hard drive of the machine I
downloaded it to?
No. To use Autoclave, you have to follow the directions
to make a bootable floppy disk, then reboot using that floppy.
- Is this program safe to use on my computer? I do not want to completely
erase my hard drive.
If you don't want to completely erase a hard drive, you shouldn't use
Autoclave. It completely erases hard drives. If you're looking to securely
erase files or free disk space, there are other utilities which do that.
I haven't tried any of these, and their inclusion here shouldn't be construed
as any sort of endorsement on my part. They're just the first utilities I found
with a quick google search:
- What's with the levels 1 through 5? Which level do I want to use?
All levels erase the disk completely. The only difference is how difficult it
would be for someone to recover data from the disk using sophisticated recovery
tools (including scanning tunneling electron microscopes). Level 1 is the
fastest, level 5 is the slowest. Level 5 is the most secure, level 1 is the
least secure. I personally couldn't recover anything from a disk that had been
cleaned with level 1, but someone with the know-how and a few thousand dollars
could. I'm not guaranteeing anything, but I doubt the NSA could recover
anything from a disk that had been cleaned with level 5. Level 3 meets most
corporate and nonclassified government erasure specifications. Here's what
each level does:
- 1 - A single pass of all zero.
- 2 - One pass of random data followed by one pass of all zero.
- 3 - Three passes: all zero, all one, all zero.
- 4 - Ten passes, some of which are random, followed by one of zero.
- 5 - 25 passes, three of which are random.
Note that none of these levels verifies that data is actually getting written
to the drive. That will be a future addition, as will a level which conforms
to DoD specifications.
- I'm using rawrite to make the bootable floppy, but there are no files
on the floppy when it finishes. What am I doing wrong?
Huh. That's weird. I'm not a Windows user myself, and I didn't write rawrite,
so it's kind of difficult for me to diagnose this sort of problem. If you could
give me more details, that would be helpful. How long did rawrite run for? Did
it look like the floppy disk was in use while it was running (lights, motor
sounds, etc)? Did rawrite give you an error message, or did it just spin for
a while and then stop? Were rawrite.exe and the autoclave image file in the
same directory?
JC Warren writes:
The question related to not getting files on the floppy is caused by the
fact that rawrite needs the -f switch before the clave03.img file on the
command line to recognize the image file.
RAWRITE option information:
-f : specify disk image file
-d : specify diskette drive to use;
must be either A or B
-n: don't wait for user to insert diskette --
assumes diskette is waiting in selected drive
-h: print this help message and exit
For example: C:\>rawrite -f clave03.img
Both files need to reside in the directory from which the utility is
launched, e.g. root of C: as above.
It may just be that you have a bad floppy disk. Try another one. If you're
using Windows (instead of DOS) to create the floppy, try using RawWriteWin--I haven't used it myself, but you might have better luck with it.
- I don't have a floppy drive. Can Autoclave run from a CD?
Probably. I haven't tried doing that yet, but I don't see why not. If you
have cd burning software which will let you make a bootable ISO-9660 disc,
use the clave03.img file as the boot image. I'll play around and see if I can
make an .iso image suitable for burning to cd, too.
- I successfully made the Autoclave floppy, but it won't boot on my
machine. What's wrong?
Can you boot your machine from any floppy? Some machines are set to only
boot from the hard disk or cdrom these days. If that's not the problem, are you
sure the floppy was made successfully? Did any of the steps in the download and
installation process give you an error message? Will that floppy boot any other
machine, or does it fail everywhere? If the floppy will boot on another system
but not on the one you want it to, please let me know what kind of machine it's
failing on. If it doesn't work anywhere, there was probably a problem in the
installation process. Give that another try. NOTE: At the moment,
Autoclave requires 16Mb of RAM to run. With less, it runs out of memory and
reboots immediately upon launching. I'll see if I can get it to work with
less, but I wouldn't hold out much hope for that.
- I cannot get past the warning screen that says I must type I understand.
You have to type exactly this: I understand. The capitalization
must be the same, there must be a period at the end, and nothing else. Don't
type the quotation marks. Don't type a space before or after. Type I
understand. and press enter or return.
- It was running for a while, and suddenly the screen went blank. What happened?
It's probably just the screensaver kicking in. Press "shift" or "control" on
your keyboard and see if the screen comes back on.
- If it's a GPL program, where's the source?
Sorry about that--it's taken forever for me to get that together, and I have
no good excuse. There's a source tar.gz file available here now. It contains the shell script which is the front end, and the
modified source of "shred" which is the back end. It doesn't include
instructions on how to build a bootable floppy out of those pieces, but once I
get good instructions written on how to do that, I'll include them.
- I have a question not answered here, or your answer doesn't work for me.
Drop me a line. My email address is below. Substitite @ for "at" and
. for "dot".
--Josh Larios <jdlarios at cac dot washington dot edu>