"Only first and last 2KB": how sure?

[Biff]

I want to erase a 3 TB external hard drive. Using "Pseudorandom Data" lasts extremely long, some days, I guess. And you cannot interrupt erasing and go on the next night as far as I know. So may be using "Only first and last 2KB" could do it. What does that option mean? How sure is it? I assume, it is very much faster than e.g. "Pseudorandom Data".

I would give the drive to a shop during the warranty time, that's why I want to make the data unreadable.

 

[sainokawara]

I do not know what you mean by "Only first and last 2KB"? To erase ALL of the data, EVERYTHING has to be overwritten and there would be no performance benefit from writing the first 2KB and then waiting for the last 2KB to rotate into position to overwrite it. A single-pass of "pseudorandom" numbers is adequate. As for how long it would take, it would depend upon the drive and how it was connected: Is it connected Firewire, SATA I, II or III or USB 2.0, 3.0? The faster the connection, the quicker it will complete. However, even the fastest connection would require HOURS for overwrite a 3 TB drive. And, yes, it canNOT be interrupted because "restarting" would resume back at the beginning.

 

[Biff]

Thank you very much, sainokawara.

I do not know what you mean by "Only first and last 2KB"?

Well, the option in Eraser.

The external drive is connected by USB 2 or 3.

To erase ALL of the data, EVERYTHING has to be overwritten and there would be no performance benefit from writing the first 2KB and then waiting for the last 2KB to rotate into position to overwrite it.

Actually it would be enough to just make the files inaccessible, so to just substitute some zeros or so. I would imagine it should be much more faster than overwriting the entire data / files.

even the fastest connection would require HOURS for overwrite a 3 TB drive.

A single-pass of "pseudorandom" numbers is adequate.

Yes, but it would last some days, I guess.

Many thanks again.

 

[sainokawara]

A file is rendered "inaccessible" when it is "deleted" but it can be "recovered" unless ALL of its data is "overwritten". For all practical purposes, there is no difference between overwriting it with zeros, ones or random bits. However, the method of "overwriting" can make a very significant difference in performance. If the device/partition does NOT contain any data that you want to keep, just do a "FULL FORMAT" and NOT a "Quick Format". That will "remove" ALL data recorded on the device. If the partition contains data you want to keep, you have to do an Eraser "Erase Unused Free Space" to overwrite just the "deleted" files.

I dislike all of the performance numbers tossed around but the maximum transfer rate of a USB 2.0 device is 60 MB/sec and a USB 3.0 device is 640 MB/sec. So, it will take a LOT LONGER to "wipe" a device connected via USB 2.0 than 3.0 whether it is done by Windows Disk Manager (Full Format) or Eraser!

 

[Biff]

A file is rendered "inaccessible" when it is "deleted" but it can be "recovered" unless ALL of its data is "overwritten". For all practical purposes, there is no difference between overwriting it with zeros, ones or random bits. However, the method of "overwriting" can make a very significant difference in performance. If the device/partition does NOT contain any data that you want to keep, just do a "FULL FORMAT" and NOT a "Quick Format". That will "remove" ALL data recorded on the device. If the partition contains data you want to keep, you have to do an Eraser "Erase Unused Free Space" to overwrite just the "deleted" files.

Alright, I understand.

I may be want to give that drive (if I get it running and then schreddered) in a warranty case to a shop, that is why the data shall be made inaccessible. So, I am wondering how the option "Only first and last 2KB" effects. How difficult might it be to recover the data erased with that option? I would assume, this option must be very much faster than erasing the drive with a single-pass of "pseudorandom" or doing a "FULL FORMAT".

I dislike all of the performance numbers tossed around but the maximum transfer rate of a USB 2.0 device is 60 MB/sec and a USB 3.0 device is 640 MB/sec.

Unfortunately there is no difference in performance with my Notebook using USB 2 or 3 (I have a Notebook with 3 USB 2 ports and 1 USB 3 port), do not know why.

 

[sainokawara]

If you did not notice any difference between connecting a device to a USB 2.0 port and a USB 3.0 port, the device itself is most likely USB 2.0. When a USB device is plugged into a USB port, they "negotiate" and operate at the lowest common mode. So, the USB 3.0 port actually operates exactly like the USB 2.0 port. This is one of the many hazzards of "performance numbers".

 

[Biff]

If you did not notice any difference between connecting a device to a USB 2.0 port and a USB 3.0 port, the device itself is most likely USB 2.0.

No, no, these external hard drives I use are USB 3 ones and the port of the Notebook is the right USB 3 port, there is a message shown after plugging in the drive, saying something like that this port can handle higher bit rates or so, USB 3. But it runs like USB 2, up to 30 MB/s.

 

[sainokawara]

If it's a USB 3.0 and 5400/7200 rpm device, I have no idea why it only runs at only 30 MB/s. This isn't a FlashDrive, is it? Some of them can be very slow! Check your product's documentation. If that doesn't answer your question, I would suggest that you post this question to a Forum associated with the external harddrive and your laptop.

 

[Biff]

This isn't a FlashDrive, is it?

Yes, it is not a Flash Drive.

Check your product's documentation

It doesn't say much more than just plug the drive in the USB 3 port. I guess, actually it should be easy like that. I do not know whether there is a special driver needed, but there is not shown one being missed or so.

Yes, a forum would be good.