Great conversation. Steve is right that the 3 wipe has a feel good factor. We do the 3 pass because its DoD sanctioned. Although that has changed for drives that contain sensitive data. They state that destruction is the only “True” way to ensure no data is recovered. If there are hard drives that your department knows has sensitive data (social security numbers, student records, payroll, etc) then PLEASE let us know when you send them over and we will shred them to ensure that nothing gets off campus. As a general rule there are certain departments that when they send computer items over we just have the drives shredded because we assume it would have sensitive data on them. We operate on the better safe than sorry principle. You can either just send me an email stating that the latest shipment coming over is the one you would like the drives shredded, or better yet is to pull the drives and put them all in a box. Then write on the box SHRED ONLY.
Wiping drives gets more complex when you start talking about SSD’s or flash drives. They have a feature called Wear Leveling. Since flash memory can only be written too so many times before it goes bad manufactures put on their flash drives and SSD’s a protocol that sits lower than the OS formatting that tells the drive where to put the data the OS is trying to write to the drive. So the OS might think it’s putting the data in a certain part of the drive but the drive tricks it and puts it on a portion of the drive that hasn’t been written too as many times. This ensures the drive lasts longer, which is great for the life of these drives but makes it a lot more difficult to ensure its properly wiped.
I’ve copied this from Wiki as they put it much better than I could ever do.
There are three basic types of wear leveling mechanisms used in Flash memory storage devices:
A Flash memory storage system with no wear leveling will not last very long if it is writing data to the flash. Without wear leveling, the Flash controller must permanently assign the logical addresses from the Operating System(OS) to the physical addresses of the Flash memory. This means that every write to a previously written block must first be read, erased, modified, and re-written to the same location. This is very time consuming and highly written locations will wear out quickly with other locations even being completely unused. Once a few blocks reach their end of life the drive is no longer operable.
The first type of real leveling is called dynamic wear leveling and it uses a map to link Logical Block Addresses (LBAs) from the OS to the physical Flash memory. Each time the OS writes replacement data, the map is updated so the original physical block is marked as invalid data, and a new block is linked to that map entry. Each time a block of data is re-written to the Flash memory it is written to a new location. However, blocks that never get replacement data sit with no additional wear on the Flash memory. The name comes from only the dynamic data is being recycled. The drive may last longer than one with no wear leveling, but there are blocks still remaining as active that will go unused when the drive is no longer operable.
The other type of wear leveling is called static wear leveling which also uses a map to link the LBA to physical memory addresses. Static wear leveling works the same as dynamic wear leveling except the static blocks that do not change are periodically moved so that these low usage cells are able to be used by other data. This rotational effect enables an SSD to operate until most of the blocks are near their end of life.
With all that said it is still possible to securely erase SSD’s and thumb drives. We use a program called eraser which basically fills the drive with nonsensical data multiple times then erases that data. So if someone was to try and extract data they would get garbled code that they think might mean something but really it’s just random files the program writes to the drives then erases.
If anyone has any other questions on how we ensure data security on campus please let me know.
Thanks
Tim Heckaman
IT Administrator
MSU Suplus Store & Recycling Ctr.
Hi Tim,
What’s the proper procedure for requesting that drives get shredded? Do we just indicate that on the salvage forms somewhere?
Thanks,
Al
From: STeve Andre' [mailto:[log in to unmask]]
Sent: Friday, July 19, 2013 5:06 PM
To: [log in to unmask]
Subject: Re: [MSUNAG] Proper Disposal of old Server hard Drives?
That was true years ago, with far smaller disks. I have read the data
from the control electronics, and you cannot get consistently readable
data from 1G+ disks. The old tricks of using nickel power in naphtha
and so on for the disks of olden days, where you could get data no
longer work.
Writing three times on modern disks has a feel-good factor. The
dod 5220.22 (dash M?) states specific things to do to erase a disk, but
I know of no disk people today who say you need to do that.
Disk technology has utterly changed in the last 15 years but the regs
for wiping them haven't.
You are right that physical destruction is best! They make for great
targets, too.
--STeve Andre'
On 07/19/13 11:17, Isaac, Jeremy wrote: