Before you can access a hard drive in your operating system, it needs to be initialized. You typically only need to initialize a hard drive if the drive is new.
A hard drive can be initialized in Windows using Disk Management. To open Disk Management, complete the following:
Windows 8 and 10
Typically, you will be prompted to initialize your hard drive, which will show up in Disk Management as a hard drive with a black bar (as opposed to a blue bar for initialized and partitioned drives). If this is the case, omit steps 1 and 2 below. If you are not prompted automatically, complete the following steps:
Note: If you are running Windows 7 or later and are using a drive larger than 2TB, initialize the hard drive with GPT. If you are running an earlier version of Windows, initialize the drive(s) with MBR. For more information, refer to the following FAQ: https://www.startech.com/en-ie/support/faqs/technical?topic=harddrives#mbr-vs-gpt.
Mac OS automatically detects hard drives that need to be initialized and will prompt you to initialize the hard drive. If you are prompted to initialize a hard drive, click Initialize. If you are not prompted to initialize the hard drive and you cannot find the hard drive in Finder, you will need to create a partition on the hard drive.
For more information on creating a partition, refer to the following FAQ: https://www.startech.com/faq/hard-drives-general-partition.