How to combine multiple discs into one

Whenever you change your computer, there is one thing that, unless it's really broken, is always saved and preserved and it's the hard disk. To avoid wasting them, it is important to know that a hard disk can be installed on another computer as a second hard disk, thus expanding the space available for the disk.
In case you have two disks with little space available or if there is a need to put all the data in a single volume, there are different ways of exploiting them as if they were a single hard disk that has available space equal to sum of the two.
There are at least 4 ways to combine multiple disks into a single volume, i.e. to make the operating system believe that the data all resides on the same hard disk. Among these, the latter is clearly the simplest, which allows you to create a large virtual unit by combining real disks and without touching the configuration of the volumes.

1) Use symbolic links

The simplest method is to use symbolic links, which are similar to normal links (those that are usually created on the desktop to launch programs) but "trick" the system into believing that that symbolic link is the file itself. This allows you to save a folder on the second disk, create the symbolic link on the first and give the computer the signal that all the files are on the first even if it is not so.
The fields of application of this trick are numerous: for example:
- Use the same folder shared between PCs with Dropbox or Onedrive
- Move the cache of Chrome and Firefox to RAM and surf faster
- Place all games downloaded with Steam on the same volume.
To find out how, follow the guide on how to create symbolic links and move folders from one disk to another .
The biggest advantage of this method is its simplicity and the ability to control the location of each specific file or folder.
If one of the disks fails, only the data on that drive is lost while the others remain intact. On the other hand, it must be admitted that it is an extremely tedious method to configure (even if, as you will see in the guide, there are programs to make them almost automatic).

2) Create a spanned volume of dynamic disks

If you have many files and folders and you want all of them to be on one volume, you can create the spanning volume or dynamic disk.
Spanned volumes are like the opposite of partitioning (i.e. dividing a hard disk into drives): a volume is created that starts from the first disk and ends at the end of the last disk, to create a single large volume. This is also often referred to as Disk Concatenation or JBOD and only works if you have more than two disks in your computer because the boot disk where the operating system is located cannot be concatenated. To create a spanned volume in Windows, it is first important to create a backup of all the data on the disks on a separate hard disk, since you need to erase them.
Open the Start menu -> Run and type diskmgmt.msc and press Enter.
Find the disks you want to merge in the main interface and, for each of them, right click and choose " Delete Volume ". Right-click on the first of the empty drives and choose " Create New Spanned Volume "
When the wizard starts, go ahead until you get to the disk selection screen and add the second, third and so on. Assign a drive letter to the new volume, format it as NTFS and name it. The management of a spanned volume is much easier than the symbolic links, because once created it behaves like a normal hard disk. When you run out of space on the first physical disk, the data automatically switches to the second. This also works with any number of units.
The biggest problem with spanned volumes is that if one of the dynamic disks breaks, the entire volume becomes unusable and all the data stored in it is lost (although some of them can be recovered). In addition, its application requires multiple disks which may not be possible on some computers. Let's say that this option (and also the creation of simple dynamic disks where partitions of the same disk are chained together instead of concatenating physical hard disks) is highly discouraged because it is very fragile and easy to fail.

3) Set up a set of disks in RAID

RAID stands for Redundant Array of Independent Disks, and offers several advantages over the spanned volume solution

• RAID is fast, reliable, protected against disk failure and there are several types of RAID. - RAID 0 is similar to a spanned volume: its main goal is to combine multiple drives into one large volume. However, instead of filling a disk before moving on to the next, it writes the data on all the drives ( Striping ). This results in a higher read speed than a slower spanned volume. In this case, however, if a disk fails, then all data is lost with little hope of recovery.
• RAID 1 is a configuration that does not serve to combine multiple disks into a single large volume but to implement a concept called mirroring : every data that is written on the main drive your computer writes the same data on the second disk. The second disk then becomes the mirror of the first and the two must have the same size. If one doesn't work anymore, it automatically goes to the second and everything goes on regularly.
• RAID 10 combines the best of RAID 0 and RAID 1: It combines several mirrored disks of the same size. However, this type of RAID requires at least 4 disks, two to combine and two others as a mirror.
• RAID 5 introduces a feature called parity, which is another method of keeping data protected from disk failure.

Unlike RAID 10, where half of the drives must be used for redundancy, RAID 5 can save recovery data in much smaller parity bits spread across all drives.
This means that you can use multiple drives for data and hopefully save some money in having to have as many disks for mirroring. RAID 5 will be much slower to write data than RAID 10. These are not the only types of RAID, but they are the most common.
To configure a RAID array there are specialized programs, often included with computer motherboards. Many people argue that hardware RAID is still more reliable and involves installing a RAID card in the PC. In this case the process varies from computer to computer and depending on the card to RAID card. In general for home use the most handy configuration is RAID 0 which however requires you to configure a parallel backup system if you do not want to lose everything in case of failure of one of the disks. RAID configurations are certainly expensive, just think that for RAID 1 it is necessary to have two identical disks and are used mainly on corporate servers.

4) Use storage spaces in Windows 10

It is a Windows 10 tool that makes it easy to combine multiple hard drives, hard drives, SSDs or USB, in a virtual drive, without difficulty and special requirements. To use this function, I refer to the guide on how to create storage spaces in Windows 10 to protect data
While combining multiple disks into a single volume or virtual drive was an operation for expert systems engineers, thanks to the storage spaces tool it made everything so simple as to give any user the opportunity to protect data by creating multiple copies without difficulty and without absolutely touching the configuration of the disks, which is always delicate.
In another article we can also see how to connect older hard drives to the computer externally.