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I first formatted my hard disk while installing CentOS.

Then again formatted the drive while installing Ubuntu.

Now, I'm about to format the drive before again coming back to Windows 10.

Will the lost data be still recoverable?

Giacomo1968
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zeeshanseikh
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2 Answers2

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First:

Now, I'm about to format the drive before again coming back to Windows 10.

No, that's not a good idea! Formatting is never part of a any data recovery procedure.

In general a quick format does create a file system without actively overwriting or zeroing existing data. I must admit I am not familiar with CentOS so it may be different and it of course matters which file system you formatted the drive with. As a rule of thumb if the format operation itself takes a relatively short amount of time it is safe to assume it was a quick format.

If I were to quick format a NTFS drive (default), much of the data is still recoverable. If we'd quick format 3 times in a row or 10 for argument sake, the exact same data will be recoverable. A full format will make data unrecoverable immediately.

If you however installed CentOS then it depends on how much data is written to the drive during this process. And it also matters where there data is written. But there's a good chance that file system meta data from the previous file system is overwritten.

Switching between file systems probably decreases the chances that for example NTFS file system structures survive the newly formatted file system. If then new data is copied, the chance that NTFS file system structures are impacted increases even more.

Then we must consider the type of drive, specially does if it supports TRIM or not. If your hard drive is an SMR drive or SSD then at least Windows format will send TRIM commands if the file system was formatted NTFS. This practically will render the data unrecoverable in most cases. If data is vital then it's is imperative to disconnect the drive from power and contact a data recovery specialist / lab.

TRIM aside it comes down to:

  • How much file system meta data was lost / overwritten. If file system meta data is largely overwritten we can still attempt recovery using the carving technique. We may be able to recover files, but file system properties such as filename are lost.
  • How much actual data was overwritten. Data that is overwritten can not be recovered. If we for example assume a 200 GB drive containing 120 GB worth of data, and with formatting and installing a new OS, 40 GB worth of data was written to the drive, we can potentially recover 80 GB worth of data.

You can only find out if data and what data can be recovered by trying. In general it's advised to clone/image the drive using a tool like ddrescue and attempt recover from the clone/image using file recovery software.

If we assume file system meta data is largely lost, a tool like PhotoRec is a good choice as it is an excellent carver. As mentioned it will not recover original file names and the folder structure.

A tool like DMDE will try file system based recovery and carving, will recover a decent amount for free, and to register and unlock almost full functionality costs only $20.

Although I think recovery is within the DIY realm, if the data is valuable I'd consider contacting a data recovery lab.

Also see: https://superuser.com/a/1758086/705502

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Really it depends what areas were overwritten. If you did a long format, it's all gone completely. If you did quick formats, then what new data overwrote old data means that part is gone. If the drive at any point was encrypted, it's gone. If it's an SSD, it's likely gone.

You could try file scavenger software to see if there's anything useful left, but really you need a data recovery company to even have a proper guess.

Tetsujin
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