I have parrot installed on a disk and debian on another disk (pentest and personal use). It is possible when i use parrot to hide my other disk ? I mean I will not mount it but I want it to be hide when I use parrot. I don’t have any trouble but it is in prevention.
If your GRUB bootloader is on the disk with Parrot installed, you could detach the Debian drive in the UEFI/BIOS, then boot Parrot.
You would have to reattach the Debian drive in BIOS to use it, and any kernel updates in Parrot will require some work with os-prober to get Debian back in the Grub menu.
I would have used LUKS encryption on both drive partitions. When in Parrot, the Debian partition could only be opened with the LUKS password/key set for it, though it may require proper user/password permissions as well to mount or read it.
All you would need to do is reinstall Debian with an encrypted root partition.