The console comes with an integrated harddrive and also supports external harddrives via USB 3.0. Using an external harddrive to store apps and games requires the drive to be USB 3.0 and storage to be 128GB or bigger.

Both, either internal or external, drive use GUID/GPT partitioning scheme and NTFS as drive format.

An external USB 3.0 drive, after being formatted on the console, is normally non-accessible on a PC due to a non-standard Boot Signature being written to the first sector of the drive.

Internal harddrive

The console supports 500GB, 1TB and 2TB harddrives (state: 09/2019). Internal harddrive uses specific partition GUIDs and partition labels.

Partitions

  1. Temp Content
  2. User Content
  3. System Support
  4. System Update
  5. System Update 2

Partition GUIDs

Name / Part Label Guid Size (bytes) Size (GB)
Temp Content B3727DA5-A3AC-4B3D-9FD6-2EA54441011B 44023414784 41
User Content variable variable variable
System Support C90D7A47-CCB9-4CBA-8C66-0459F6B85724 42949672960 40
System Update 9A056AD7-32ED-4141-AEB1-AFB9BD5565DC 12884901888 12
System Update 2 24B2197C-9D01-45F9-A8E1-DBBCFA161EB2 7516192768 7

User partition GUIDs

Harddrive size Guid Partition size (bytes) Partition size (GB)
500 GB A2344BDB-D6DE-4766-9EB5-4109A12228E5 391915765760 365
1 TB 25E8A1B2-0B2A-4474-93FA-35B847D97EE5 838592364544 781
2 TB 5B114955-4A1C-45C4-86DC-D95070008139 1784558911488 1662

External harddrive

When a USB 3.0 drive is formatted for apps/games usage by the console, it gets rendered unreadable by a PC by writing a special, non-standard boot signature.

By overwriting the custom xbox signature with the regular, expected bytes makes the drive being recognized and mountable on a PC.

Boot signature marker

The boot signature is located in the first sector of the drive at offset: 0x1FE

Type Boot signature
Regular (MBR) 55 AA
Xbox One 99 CC

Note: Even if 55 AA indicates MBR normally, for GPT it is just marking the "Protective MBR", to secure GUID partition against ovewriting by non-GPT aware applications.