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I am returning my laptop to the retailer but I have had it for 1 month, In this time I have stored some confidential information, Because of this I am planning to zero fill my SSD using http://cmrr.ucsd.edu/people/Hughes/secure-erase.html or https://www.piriform.com/defraggler

Once I have done the zero fill, will I be able to easily install windows 8.1 back on it? By easy I mean a normal approach, possibly involving some formatting/partitioning.

I must be able to install windows 8.1 because the retailer will check to see if it works.

I am not concerned that zero filling can reduce the SSD read/write cycles as the laptop is faulty in other areas anyway.

An except from Secure Erase Q&A page states

Q:  What is the difference between secure erase and enhanced secure erase?

A:  Secure erase overwrites all user data areas with binary zeroes.  Enhanced 
secure erase writes predetermined data patterns (set by the manufacturer) to 
all user data areas, including sectors that are no longer in use due to 
reallocation. ***NOTE:  the enhanced secure erase option is not supported by 
all ATA drives.

Am I going about this the wrong way, is there something better I should do?

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  • I am no expert on this but I think secure deleting a SSD is not easy and depend on what drive you have. The drives firmware makes it impossible for you to overwrite each block and there is mostly no way of checking what the firmware does. There are some encrypted drives where you can change the encryption key to "delete" all data for sure.
    – PiTheNumber
    Jan 5, 2015 at 15:44
  • When you re-install your operating system, use full-disk encryption and you won't need to worry about this again.
    – Johnny
    Jan 5, 2015 at 20:15

3 Answers 3

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Your approach is flawed.

You will only zero-fill the remaining free space of the SSD because you're doing it from the OS. That is bad in many ways, as the OS itself can have remnants of your confidential files in its caches/event logs/whatever, and this utility won't erase them because technically they are still a file.

You should use a Linux live-CD instead, and erase the whole disk multiple times using the following command : shred -v /dev/sdX which would rewrite the SSD three times using random data.

You can also try, in addition to the above approach (technically the secure erase command should suffice, but its implementation might be flawed so we still keep the 3x overwrite mentioned above), the ATA secure erase command :

First check to make sure the disk's security status is not "frozen"; some laptops with disk password support in the BIOS freeze the disk to prevent the OS from disabling/changing that password :

hdparm -I /dev/sdX

If the command says "frozen", you should try suspending the system. On next boot, the drive will be reset to its default state due to the loss of power and won't be frozen again because the BIOS isn't executed.

Now, let's do the actual erase :

hdparm --user-master u --security-set-pass verysecure /dev/sdX
hdparm --user-master u --security-erase verysecure /dev/sdX

The first command sets a security password which is necessary to perform any security-related commands, the second command issues the secure erase command do the drive. You don't have to be worried about the machine asking for the password on next boot since the secure erase command also clears that password.

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  • You can provide a -n option to shred to provide the number of iterations to perform.
    – RoraΖ
    Jan 5, 2015 at 14:25
  • >.< I need to learn to read entire sentences.
    – RoraΖ
    Jan 5, 2015 at 14:28
  • @raz no problems, it happens to everyone. :)
    – user256743
    Jan 5, 2015 at 14:29
  • this is a great answer, well done
    – user409554
    Jan 19, 2015 at 22:50
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You will be able to reinstall Windows 8.1 after using Zero Fill software, don't worry about it.

And even if you are worried about the write count on your disk, some other users may be worried. You (and the others) don't need to be concerned. Those guys wrote lots and lots of data to some SSDs before they failed. A Zero Fill software will not create any wear on the drive.

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Read this article about SSD endurance testing. It means you can write many GB per day for several years. Of course some disks will fail to meet this, but overall this should work out for almost all disks. Your one time secure erase won't harm it.

Grueling endurance test blows away SSD durability fears

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