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I am downgrading a laptop from windows 8 to windows 7, but in order to do so I have to use diskpart clean. The disk has several partitions, namely a system partition and a data partition.

Will diskpart clean destroy the existing data in the data partition?

dtech
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  • If you don't clean the data partition you will not lose data, but before doing any partition modifications you have to be prepared to lose your entire disc, so you must create a disc image before you embark on this sort of task: it is very easy to make mistakes, as I know all too well. To make recovery easier, take a separate copy of your data partition. You cannot have too many back-ups. – AFH Jan 07 '17 at 16:19
  • Damned windows 8 is like a tick. Can't install windows 7 on a gpt partition, the partition with the install is already formatted, now I'm xcopying the files on a flash drive under command prompt so I can diskpart clean... – dtech Jan 07 '17 at 16:35
  • "Can't install windows 7 on a GPT partition" - You do realize that it actually is possible to install Windows 7 on a GPT partition right? – Ramhound Jan 07 '17 at 16:45
  • @Ramhound - the installer says it can't. The how-to's I found all include the diskpart clean step. – dtech Jan 07 '17 at 16:54
  • Your booting the installation in UEFI mode, and trying to install a 64-bit version of Windows 7, if both of those are true Windows 7 supports GPT. "the installer says it can't. " - doesn't tell me anything, provide the exact message, I am telling you Windows 7 supports GPT. – Ramhound Jan 07 '17 at 17:21
  • @Ramhound - will see about that after I make a backup, just in case. – dtech Jan 07 '17 at 17:34
  • @Ramhound the problem is that the USB flash doesn't show up without CSM, so it tries to install in legacy bios mode. – dtech Jan 07 '17 at 18:55
  • If a USB 2.0 flash drive isn't showing up unless you enable CSM then its not configured to be a EFI drive. Use Rufus to create it – Ramhound Jan 07 '17 at 19:17
  • That's what I am doing now, I've already done it actually, but for some reason after I select gpt and then select the image, the partition scheme resets back to mbr, which I didn't notice the first time. – dtech Jan 07 '17 at 19:19
  • @Ramhound - and it never ends. Now the flash is recognized as uefi bootable, but "windows failed to start blah blah recent hardware or software change..." : efi/microsoft/boot/bcd status: 0xc00000d - an error occurred while attempting to read the boot configuration data. – dtech Jan 07 '17 at 20:22
  • You need to format the drive, so there are no partitions on the drive, before you attempt to install Windows. I hope you understand that, there isn't a mechanic to go from Windows 8 to Windows 7, unless you format the drive. All your other solution does would allow Windows 7 to install in Legacy Mode, and you would end up with MBR partitions. – Ramhound Jan 07 '17 at 20:26
  • @Ramhound - I have formatted the system partition. The idea here is to keep the data partition in tact. I was able to boot from the flash in csm mode, and despite a warning about gpt it is now installing, hopefully that will work. – dtech Jan 07 '17 at 20:35
  • "The idea here is to keep the data partition in tact." - Can you migrate the data to another drive, do as I suggest install Windows on the unallocated partition, then create the data partition after Windows 7 is installed? You currently have a GPT or MBR HDD? – Ramhound Jan 07 '17 at 20:38
  • Let us continue this discussion in chat. – dtech Jan 07 '17 at 20:39

2 Answers2

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Will diskpart clean destroy the existing data in the data partition?

diskpart clean will remove any and all partition or volume formatting from the disk with focus.

diskpart clean all will zero the disk.

Further Reading

DavidPostill
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No, diskpart clean won't destroy the data, it just deletes the partition table. You can recover the lost partitions using the excellent testdisk utility, by using testdisk's "Quick Scan" feature. Testdisk comes preinstalled on the GParted LiveCD

Also avoid the "Minitool" worthless recovery tool which has pages with harmful advice on how to destroy your partitions and then tries to sell you their scam recovery tool to get the partitions back.

To convert MBR partitions to GPT, use the gdisk tool which is also found on the GParted LiveCD.

gregn3
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  • Note that clearing the partition information effectively deletes all the data. You WILL end up having to recover the data after performing a clean. – music2myear Nov 28 '22 at 04:27