Got too much data for your preferred drive? Here's what to do

By J. Carlton Collins, CPA

Q. My computer has three 1 TB hard drives, but I have 1.5 TBs of data that won't fit on a single drive. In this case, should I replace one of my drives with a larger hard drive or just purchase a new computer?

A. I assume your goal is to organize all your data files on a single drive letter, such as the D drive, for example. If so, you don't need to purchase a new hard drive or a new computer to achieve this goal. You can create a single drive letter for storing your data files across all of your hard drives as follows. Right-click the Windows 10 Menu button and select System, Storage, Manage Storage Spaces, Create a new pool and storage space. Windows 10 will search your computer for all available hard drives. These drives can be internal or external hard drives, or even solid-state drives. You can also combine a variety of drive types, such as USB, SATA, and SAS drives, to accomplish this feat. For example, if you have three drives of 1 TB each, you could create a 3 TB virtual drive, officially referred to as a Storage Pool, using these three 1 TB hard drives. As if that weren't nifty enough, you could even create a 4 TB or a 5 TB virtual drive from your three 1 TB hard drives, and as the virtual drive begins to fill up, you will be notified to install more hard drives to increase your available hard disk space. To create your new storage space on a ­Windows 10 computer, continue by providing a Name, Drive letter, File system, Resiliency type, Size, and then click the Create storage space button at the bottom of the screen, as pictured below.



Although the ability to group different drive technologies of differing sizes is a nice feature, it's not the main reason CPAs typically use the Storage Space tool. Primarily, CPAs create virtual storage spaces so they can then configure different types of data protection (referred to as "resiliency") on their hard drives, as follows:

  1. Simple resiliency: While this option will combine your hard drives into a single virtual drive, it does nothing to protect the data. It merely writes one copy of the data across all your hard drives, and if a single drive fails, you will lose at least some of your data.

  2. Two-way mirroring resiliency: This option will write two copies of the data across your physical hard drives in such a way that it protects the data from a single drive failure. Two-way mirroring requires at least two physical drives. If one drive fails, the redundant files on your remaining hard drives will allow you to recover all the data files.

  3. Three-way mirroring resiliency: Similar to two-way mirroring, this option writes three copies of the data across your physical hard drives, which will help to protect the data from two simultaneous drive failures. Three-way mirroring requires at least three drives.

  4. Parity resiliency: Similar to the standard RAID 5 technology typically found in network servers today, this option doesn't make duplicate or triplicate copies of your files as discussed above, but it does write parity information across your physical hard drives, which allows Windows 10 to reconstruct the data files (using the parity bit information) so you can recover the data from a single drive failure. As a simple example, if the bits 0, 1, 0, 1 are saved on two hard drives, then a checksum parity bit (2 in this example because 0+1+0+1=2) is saved on the third drive. Thereafter, if one bit is lost, the check bit can be used with the three remaining bits to recover the missing bit. (For example, if one drive fails and the bits 0, 1, 0, ? must add to 2, then the computer can calculate that the missing bit must be a 1.) This option requires a least three drives.

If your goal is merely to create one virtual drive from multiple hard drives, then simple resiliency may be the best option. However, if your computer files are mission critical (which means you don't even have time to restore backups should the need arise), then you should select one of the other resiliency options. In this case I usually recommend two-way mirroring. While three-way mirroring offers greater protection, its downfall is that it uses more storage space. The parity resiliency option uses the least amount of storage space, but some CPAs reject this option because the data reconstruction process sounds daunting. In fact, the reconstruction process is almost exactly like uncompressing (or extracting) a set of compressed data files.

It is important to note that in no event do these data protection options negate the need for regular or continuous backup procedures, because these resiliency measures do not prevent data loss in the event of fire, theft, or malware.

About the author

J. Carlton Collins ( is a technology consultant, a conference presenter, and a JofA contributing editor.

Submit a question

Do you have technology questions for this column? Or, after reading an answer, do you have a better solution? Send them to We regret being unable to individually answer all submitted questions.


Get your clients ready for tax season

Upon its enactment in March, the American Rescue Plan Act (ARPA) introduced many new tax changes, some of which retroactively affected 2020 returns. Making the right moves now can help you mitigate any surprises heading into 2022.


Black CPA Centennial, 1921–2021

With 2021 marking the 100th anniversary of the first Black licensed CPA in the United States, a yearlong campaign kicked off to recognize the nation’s Black CPAs and encourage greater progress in diversity, inclusion, and equity in the CPA profession.