Why does my hard drive size appear smaller on Synology Unified Controller?

Details

On DSM UC go to Storage Manager > Volume. The hard drive size appears smaller than that claimed by the HDD manufacturer because operating systems (of Synology Unified Controller or regular computers) adopt the binary definition of storage units while HDD manufacturers adopt the decimal definition.

Decimal definition (adopted by HDD manufacturers):	Binary definition (adopted by file systems):
1 TB = 1000 GB; 1 GB = 1000 MB; 1 MB = 1000 KB; 1 KB=1000 Bytes	1 TB = 1024 GB; 1 GB = 1024 MB; 1 MB = 1024 KB; 1 KB=1024 Bytes
Reflected size: 1 TB = 1000⁴ Bytes and 1 GB = 1000³ Bytes.	Reflected size: 1 TB = 1024⁴ Bytes and 1 GB = 1024³ Bytes.

As a result, if you buy two hard drives labeled as 500 GB and 1 TB and install them on your Synology Unified Controller, the actual size for each drive displayed on the Volume page will be as follows:

500 GB x 1000³ / 1024³ = 465 GB

1000 GB x 1000³ / 1024³ = 931 GB

Was this article helpful?

Yes ／ No