Translation guide
A data storage device used in computers. In Japanese, the term is usually expressed with the loanword ハードディスク or the abbreviation HDD.
hard disk
Often abbreviated as HDD (エイチディーディー) in technical contexts.
Referring to the physical storage device inside a computer or external enclosure.
The most common and direct translation. Used in both technical and everyday contexts.
The hard disk is running out of space.
I bought an external hard disk.
Abbreviation for Hard Disk Drive. Common in technical contexts, product specs, and among enthusiasts.
I replaced the HDD with an SSD.
Full form of HDD. Rarely used in conversation; mostly seen in formal documentation.
The cause is a hard disk drive failure.
Talking about the amount of storage or comparing with other storage types like SSD.
Used when discussing storage space or type, often in contrast with SSD.
This PC has a 1TB hard disk.
In casual conversation, ハードディスク is perfectly natural. HDD is common in written specs or when comparing with SSD. Avoid the full ハードディスクドライブ unless in a formal report.
SSDs are faster than hard disks.