Hi Jitender,

If you use a Spanned volume, you can combine two or more hard drives of different sizes to create one large volume. On Spanned, drives are utilize sequentially, meaning data won't be written to the second hard drive until the first hard drive is full.
On the other hand, if you use a Striped volume, you can also combine two or more hard drives to create one large volume. However, if you want to use the entire available space, you'll need to use hard drives of the same size. On Striped, data is written across all participating drives, offering better performance than the Spanned option.

It's important to note that you will erase the content of the hard drives participating of the Spanned or Striped volume, as such make sure to backup the data before proceeding.

1. Use the Windows key + X keyboard shortcut to open the Power User menu and select Disk Management.
2. Right-click the hard drive volume and select Delete volume.
3. Click Yes to confirm the deletion of the current volume and all its content.
4. Repeat steps 2 and 3 on the hard drives you want to combine.
5. Right-click the unallocated space of the drive and select New Striped Volume (or New Spanned Volume).
6. Click Next.
   
7. Select the additional disks, one by one, and click Add.
8. Click Next.
   
9. Leave the default drive letter assignment and click Next.
10. Make sure the file system is set to NTFS, allocation unit size is set to default, and choose a volume label.
11. Check the Perform a quick format option.
12. Click Next.
    
13. Click Finish.
    
14. You'll be prompted to convert the hard drive from basic to dynamic, click Yes to complete the task.
    

    

I hope this helps.

Regards,
Lokesh