I bought a Fujitsu Celvin Drive D100 (external USB HDD) as new and now I want to partition and format it for Linux use. I noticed however that at the factory they have left some empty space before (1 MiB) and after (2 MiB) the single NTFS partition. I called the Fujitsu helpdesk and they didn't seem to know why the unformatted space is there but – of course – recommended that I leave things as they are. Could there be something crucial hidden there or are the empty areas there for (data) safety reasons? Can I use the entire disk without problems? Please don't question my reasons for wanting 3 extra megabytes on a 2 terabyte HDD, I only want some information. ;-)
My first guess would be that they are some kind of reserved partitions for the external enclosure, but you said Fujitsu didn't know why they were there. I would leave them alone just for warranty purposes and to make sure it keeps working with the enclosure. It's only 3MB.
If you plan on taking the HDD out of the enclosure in the future, then remove them at that time.
I would expect that the first 1MB that is unallocated is because modern partition managers take account of the fact that they may be creating a partition on either a drive with 4kb sectors or an SSD and so the partition manager (for simplicities sake) will use a "one size fits all" approach rather than working out all the possible variations that will work for each type of drive.
Both the 4kb Advanced Format drives and SSDs require the partitions to be aligned to the cluster (or SSD erase cell) for optimum performance and the 1MB gap at the start of the disk is a nice common figure that will work for both types.
Heck on a several hundred gigabyte drive 1MB is nothing to worry about.
As to the 2MB at the end of the drive, chances are that whatever partition manager was used simply rounded up or down some particular number and ended up with a small bit of space left over at the end of the disk when it created the partition. I've seen it happen quite often on various drives and from various operating systems partition managers.
In the long run you probably shouldn't care as 3MB is an absolute tiny amount of space compared to modern many-hundred-gigabyte drives and reclaiming it is not really going to mean you can store that much more data, maybe 1 mp3 or a some documents.
I'm the same person as the original poster; I just created an account so I can't select the best answer and whatnot.
I did something like Synetech inc. suggested. The beginning of the drive contains a boot sector of some kind and then this hexa string over and over again: e8 97 d1 c3. The end of the drive is just zeros. I read JdeBP's link and it now seems that the extra space is there just because some Windows partitioning tool likes to do it that way (to make the drive efficient). I think I can use the whole hard drive (leaving space for a boot loader) without problems as no-one reported them. I can't imagine this drive uses Advanced Format but better play it safe by using 8-sector limits.
This is how I made a back-up of the drive:
Then I put everything in a compressed archive file. I can restore the drive to its current state should a warranty issue arise. Thanks for everyone's input.