this post was submitted on 16 Dec 2023
56 points (95.2% liked)

Selfhosted

40201 readers
567 users here now

A place to share alternatives to popular online services that can be self-hosted without giving up privacy or locking you into a service you don't control.

Rules:

  1. Be civil: we're here to support and learn from one another. Insults won't be tolerated. Flame wars are frowned upon.

  2. No spam posting.

  3. Posts have to be centered around self-hosting. There are other communities for discussing hardware or home computing. If it's not obvious why your post topic revolves around selfhosting, please include details to make it clear.

  4. Don't duplicate the full text of your blog or github here. Just post the link for folks to click.

  5. Submission headline should match the article title (don’t cherry-pick information from the title to fit your agenda).

  6. No trolling.

Resources:

Any issues on the community? Report it using the report flag.

Questions? DM the mods!

founded 1 year ago
MODERATORS
56
Proper HDD clear process? (poptalk.scrubbles.tech)
submitted 11 months ago* (last edited 11 months ago) by scrubbles@poptalk.scrubbles.tech to c/selfhosted@lemmy.world
 

Usually my process is very... hammer and drill related - but I have a family member who is interested in taking my latest batch of hard drives after I upgraded.

What are the best (linux) tools for the process? I'd like to run some tests to make sure they're good first and also do a full zero out of any data. (Used to be a raid if that matters)

Edit: Thanks all, process is officially started, will probably run for quite a while. Appreciate the advice!

you are viewing a single comment's thread
view the rest of the comments
[–] Vilian@lemmy.ca 1 points 11 months ago (2 children)

why don't just zeroes from the start?, instead of using random data and them zeroes it?

[–] MeanEYE@lemmy.world 6 points 11 months ago* (last edited 11 months ago)

Like u/MrMcGasion said, zeroing makes it easier to recover original data. Data storage and signal processing is pretty much a game of threshold values. From digital world you might see 0 or 1, but in reality it's a charge on a certain scale, lets assume 0 to 100%. Anything above 60% would be considered 1 and anything below 45% a 0. Or something like that.

When you do zero the drive, that means drive will reduce charge enough to pass the lower limit, but it will not be 0 on any account. With custom firmware or special tools it is possible to configure this threshold and all of the sudden it is as if your data was never removed. Add to this situation existence of checksums and total removal of data becomes a real challenge. Hence why all these tools do more than one operation to make sure data is really zeroed or removed.

For this reason random data is better approach is much better than zeroing because random data alters each block differently instead of just reducing charge by a fixed amount, as it is with zeroing. Additional safety is achieved by multiple random data writes.

All of this plays a role only on magnetic storage, that is to say HDDs. SSD is a completely different beast and wiping SSD can lead to reduced lifespan of the drive without actually achieving the desired result. SSDs have write distribution algorithms which make sure each of the blocks are equally used. So while your computer thinks it's writing something at the beginning of the drive, in reality that block can be anywhere on the device and address is just internally translated to real one.

[–] MrMcGasion@lemmy.world 3 points 11 months ago (1 children)

Just doing a single pass all the same like zeroes, often still leaves the original data recoverable. Doing passes of random data and then zeroing it lowers the chance that the original data can be recovered.

[–] Moonrise2473@feddit.it 6 points 11 months ago

The "can" in can be recovered means "if a state sponsored attacker thinks that you have nuclear secrets on that drive, they can spend millions and recover data by manually analyzing the magnetic flux in a clean room lab" not "you can recover it by running this program"