Understanding Data Discrepancies on External SSDs: A Cautionary Tale

Recently, I made the transition to a new PC and decided to invest in a 4 TB external SSD, opting for a more convenient storage solution for my files. My previous system relied on an internal HDD, but I found that moving to an external SSD would simplify future upgrades and potentially lead to a later switch to a Network Attached Storage (NAS) system.

I purchased the Crucial X9 Pro 4TB Portable SSD, which has garnered excellent reviews online, particularly on Amazon. To manage the data transfer, I utilized a utility called RichCopy, developed by Ken Tamaru at Microsoft. Although discontinued, it remains a powerful file copying tool, capable of handling large batches of data efficiently.

Upon completing the transfer of 1.48 TB of files, I was taken aback to discover that the SSD had recorded a usage of 2.96 TB. This raised several questions about how that much space was consumed. Each folder seemed to match in size when I reviewed them individually, apart from a couple of minor discrepancies where a few files appeared either on the source or the destination.

Here are my preliminary theories regarding this unusual situation:

1. There may be some residual or phantom data that hasn’t been adequately cleared from the SSD, necessitating a clean-up.
2. The differences in the file systems—NTFS for the internal HDD versus exFAT for the SSD—might be causing unexpected behavior.
3. The SSD could potentially be defective.

To clarify the situation, I ran a size check in the folder settings, which piqued my curiosity when I saw a notable difference between the “Actual Size” and the “Size on Disk.” This discrepancy led me to explore further using a tool called TreeSize, only to find an alarming contrast between the actual data size and the allocated space on the drive.

After conducting some research, I discovered that the variances in formatting between exFAT and NTFS could be influencing my data usage metrics. The allocation unit sizes for each file system—4,096 bytes for NTFS and a much larger 1,024 KB for exFAT—seem to be a significant factor.

Given these insights, I’m considering reformatting the SSD to an NTFS file system with a 4,096-byte allocation size to see if this resolves the issue.

If anyone has encountered a similar issue or has insights into