These small unallocated spaces at the beginning and/or end of hard drives are created under various circumstances for "housekeeping" purposes by the OS.
You should leave them alone unless you know what you are doing.
Here is a typical explanation from Acronis:
Re: Small unallocated space automatically created
Hello all, Thank you for choosing Acronis Disk Director.
Please accept our apologies for the delay with the response.
churin, the exact size of the space created is not clear from message.
However, let us explain one thing, it is related to 7,8 MB's of unallocated space on each drive.
There are two situations in which partitioning software (i.e. Acronis Disk Director) can detect an area of unallocated space of up to 7.8 MB in size that was not created there manually:
1. Up to 7.8 MB (minimum of 1MB) of unallocated space resides in the end of the hard disk. This area is reserved by Windows (NT family) operating systems for the purpose of creation of Dynamic Disk structures. This unallocated space area is not shown by Windows Disk Management; however Acronis Disk Director is able to merge it with an adjacent partition. Therefore, after doing that there can be problems with creating Dynamic Disk structures.
2. Exactly 7.8 MB of unallocated space reside in the beginning of the hard disk. Normally this means that there are no Primary partitions on the hard drive and the hard drive contains an Extended partition only. In such cases Windows reserves the minimal amount needed for creating a partition (7.8 MB) in order to be able to handle the only Extended partition properly. It is not recommended to remove this area. Even though technically it is possible to merge it with the Extended partition, this may result in the data on it becoming inaccessible.
Detailed information about Acronis Disk Director product can be found in User's Guide.