Methods to securely delete data from tape

[erics_1]

All,

I'm researching ways that we can safely delete contents on tape media we have before it is reused. Now, LTT offers a 3 level 'erase' function for DDS and LTO which is helpful but DLT is not supported by that function for some reason. I offered several options for degaussers to management but was turned down because of the cost involved. I know I can run dd against the tape but that ties up a drive for over a day before completing. This interferes with nightly backups. I'd like your input as to any solutions you may have implemented.

Thanks,
Eric

[Steven E. Protter]

Shalom,

A very powerful magnet has always done us well, at least in my prior job.

Where I work now, we're so security conscious that we simply won't resell old tapes no matter what their dollar/shekel value.

All old tapes and disks are physically destroyed at end of life.

SEP

[Peter Nikitka]

Hi,

I think ou to set priority first:
- low costs
=> reuse of tapes
=> no physical destroying
- high security
=> buy degauss equipment
OR
=> destroy tapes physically

Both aspects could be done via
dd if=/dev/random of=/dev/lto bs=5k

but since you have another one:
- no availability (time to erase or additional drive)

... you have to decide!

mfG Peter

[Steven Schweda]

Do I have this right? A bulk tape eraser
costs too much, but doubling the
wear-and-tear on the actual tape drive is OK?
Yikes.

For erasing a tape well, fire is good. If you
plan to do anything less effective than that,
then a large permanent magnet is probably
about as good as anything. It all depends
on what's good enough, that is, whom you are
trying to stop from reading the tape.

[Bill Hassell · Accepted solution]

You have to define the level of security you need. For instance, you can remove all access to DDS tapes by simply writing a 1-line file at the beginning of the tape. Now, none of the trailing data is accessible. The DDS standard defines the last write that occurs before closing and rewinding the tape as the end of the media. No amount of mt positioning commands will move past the last record on the tape. This limitation is in the firmware so tinkering with the drive electronics won't get past the end-of-data marker.

Now this is where the importance of protecting the old data comes in. A very determined hacker can try positioning the tape and powering the drive off under certain conditions. Or the tape can be sent to a data recovery company where they have special firmware to recover unreadable data .

And note that degaussing modern tapes can create problems with the tape. If the tape is to be thrown away, then a simple degausser will work just fine. Only companies with enormous budgets can afford the equipment needed to read data that has been overwritten or degaussed.

So how important is the data and what is your company's exposure should the data be stolen? Generally speaking, the importance and liability is far more than the cost of the tapes -- which means destruction (crushed, chipped or incinerated) is by far the safest and cheapest method. I would not waste the time and wear using some program to erase the tapes.

[erics_1]

All,

Thanks for your input and insight. I think I'll make another push for a degausser.

Thanks again,
Eric