Hi,I want to dual boot Linux Ubuntu with Windows 8.1.I want to take 60 GB of my D: partition which is HDD.I am worried if I resize my disk (take 60 GB for new EXT 4 partition) will there be a problem with resizing it again?I mean, if Linux installation maybge fail or something will there be a problem to join these 60 GB again D: drive.I am worried because my data is very important to me and i think that some space (from that 60 GB) won't come back in.I took 60.000.000 but when i want to return it again it will be 59.999.998 or something.I don't want that some space is not used.That happend to me with my USB.Now i have 7.00 MB of unused space on USB(FAT32).I want that my hard disk work fully.Sorry for my bad english.
There should be no problem with resizing the existing partition and then creating a new partition from it and then at some point undoing that if you want. Of course, very little is ever guaranteed to go 100% correct 100% of the time. So, while you should not have an problems, it is still possible that something odd may happen.
The first thing to keep is mind is that adjusting partitions with either the Windows tool or a third party tool is doing a major operation on the disk. While such operations tend to happen without a hitch, some times things go wrong. So, at the very minimum, it is a good idea to backup your data on any drives that house the partitions you are going to mess with. This is especially true if the partitioning is going to be destructive (i.e. essentially needs to wipe the drive to a blank state to then create the new partition scheme), which can be true for some third party partition tools. The built-in Windows partition tools is non-destructive by default (i.e. you can shrink a partition as long as there is empty space on the partition and then create a new partition from the resulting unallocated space or you can expand a partition into any adjacent unallocated space), but can be used in a destructive manner if you desire. And in theory, non-desctructive partitions does not need for the data to be backed up...but I still strongly recommend it.
The key thing to remember with non-destructive partitioning is that any unallocated space that you want to use to extend a partition has to be "adjacent" to it. Imagine your drive as a long line of blocks of colors like how it is represented in Disk Manager or other partition tools. If you shrink a partition (a block of color) that is at the end of the line so that it is shorter followed by a new block of color, then the new block of color at the end of the line cannot be "merged" (aka used to extend) with another block of color that is located in the middle of the line. They have to be right next to each other.
And that seems to be your case. You seem to want shrink the partition at the end of the disk and then create a new partition from the newly unallocated space. And if/when you decide you don't want to play with Linux anymore, you then might change that EXT 4 partition back to unallocated space so that you can then re-extend the partition your shrunk.
As I said, in theory, you should have no problems and no lose any disk space, but I cannot 100% guarantee it. If you want to be sure, then there are some things you can do...
1st option is to just run Linux in a virtual machine and not mess with the partitions at all. You can do that for free with VirtualBox.
2nd option is to install a second drive and install Linux on the second drive. With this option, if you decide you are done with Linux, then you just reformat the drive (and remove if you don't want to use it for other purposes as an internal drive). If you go this route, you can either do this with all other drives temporarily disconnected or with them still connected. Personally, I do the former with my multiboot systems. This will install the new OS as if it is a single drive and NOT install a boot manager. I then just use the built-in option of my motherboard to pick which drive from which I boot. If you do the latter, then it will install a boot manager on the primary boot drive that will then let you pick which OS to boot from. Either way, this option again means that you do not mess with the partitions of your current drives. This option would not be free as you would need a second drive, which would cost money unless you already had a second blank drive.
3rd options is to clone your current drive that you want to adjust the partitions on. This again would require a second drive (preferably of the same brand and model/size as the drive currently in there). This has the advantage of backing up your current drive in a manner that makes an EXACT duplicate (if the same brand and model/size...otherwise a virtual exact duplicate) of your current setup. When you decide you are done with Linux, you could then re-clone from the clone drive back to the main drive to get back to exactly where you were. The main downside of this approach is that the clone drive will not have any updates to the Windows OS, programs, and new/changed data files on the main drive. This means before restoring the old setup, you would need to copy any new or changed data files from the main drive to the cloned drive and then still update Windows and/or programs and install again any newly installed programs. And, of course, you would need to buy a second drive if you already do not have one.
4th option is to "play" with Linux on a LiveCD or maybe a bootable external USB or flash drive.