Flash Filesystem

NAND structure

Boot Partitions

Boot Partition 0 (0 of 1)

Offset	Size	Description
0x000000		Title 0100000000000819 BCT
0x004000		Title 010000000000081A BCT
0x008000		Title 0100000000000819 BCT
0x00C000		Title 010000000000081A BCT
0x100000		Title 0100000000000819 "package1"
0x140000		Title 0100000000000819 "package1" (Backup)
0x180000		Keyblob area, the first 0xB0 is identical to the console-unique "customer data" section in BCTs
0x184000		Unknown, 0x20-bytes hash + one u64? All zero on 1.0.

Boot Partition 1 (1 of 1)

Offset	Size	Description
0x000000		Title 010000000000081A "package1"
0x040000		Title 010000000000081A "package1" (Backup)

User Partitions

Partition name	Offset	Size	Bis Partition ID	Description
N/A	0x0		20	GPT header, Bis-storage also allows raw access to the entire NAND eMMC sectors starting at sector0.
PRODINFO	0x00004400	0x003FBC00	27	"CAL0" raw partition containing set:cal data
PRODINFOF	0x00400000	0x00400000	28	FAT12 filesystem, additional calibration?
BCPKG2-1-Normal-Main	0x00800000	0x00800000	21	For all these packages, data starts at offset 0x4000 and is not console-unique. This is installed from "package2": on retail it's from FIRM-A 0100000000000819, for unknown cases it's from FIRM-C, 010000000000081B.
BCPKG2-2-Normal-Sub	0x01000000	0x00800000	22	Identical to BCPKG2-1-Normal-Main, probably used as a backup partition.
BCPKG2-3-SafeMode-Main	0x01800000	0x00800000	23	This is installed from "package2" in firmware package B, 010000000000081A.
BCPKG2-4-SafeMode-Sub	0x02000000	0x00800000	24	Identical to BCPKG2-3-SafeMode-Main.
BCPKG2-5-Repair-Main	0x02800000	0x00800000	25	Unknown what title this originates from.
BCPKG2-6-Repair-Sub	0x03000000	0x00800000	26	Identical to BCPKG2-5-Repair-Main.
SAFE	0x03800000	0x04000000	29	FAT32 filesystem
SYSTEM	0x07800000	0xA0000000	31 (and 32?(Error 0x2EE202 is returned for 32))	FAT32 filesystem
USER	0xA7800000	0x680000000	30	FAT32 filesystem
	0x747BFFE00	0x200		This is the backup GPT header specified by the main GPT header. This is also the last sector readable with Bis-storage paritionID 20.

NCAs stored in NAND are raw, identical to the data readable with Content_Manager_services#ReadEntryRaw.

PRODINFOF

PRODINFOF
├── Certifications
│   └── WirelessCertification.png
└── ptd
    ├── DeviceIdWithEmsBit.dat
    ├── Ecid.dat
    ├── prodCode.dat
    └── log
        ├── Process_asm1.log
        ├── Process_board1.log
        ├── TestFlagLine.log
        ├── TestFlagQc.log
        ├── AGING
        │   └── Sequence.log
        ├── BOARD_TEST
        │   └── Sequence.log
        ├── BOARD_WIRELESS
        │   └── Sequence.log
        ├── FINAL_CHECK
        │   └── Sequence.log
        ├── LCD_AND_KEY
        │   └── Sequence.log
        └── USB_AND_HP
            └── Sequence.log

DeviceIdWithEmsBit.dat

Contains a 0x10-byte uppercase hex string, identical to the DeviceId in the DeviceCert.

SYSTEM

SYSTEM
├── PRF2SAFE.RCV
├── Contents
│   ├── registered
│   │   └── ... NCA
│   └── placehld
│       └── ... NCA
├── save
│   └── ...
└── saveMeta
    └── ... (empty?)

The saves stored under this partition are only for system-titles / etc.

USER

USER
├── PRF2SAFE.RCV
├── Album (Same layout as SD)
├── Contents
│   ├── registered
│   │   └── ... NCA
│   └── placehld
│       └── ... NCA
├── save
│   └── ...
└── saveMeta
    └── ... 

The saves for all non-system applications, regardless of where the application is located(storageID), is stored here. May include other saves too.

SAFE

SAFE
├── PRF2SAFE.RCV
├── Contents
│   ├── registered
│   │   └── ... NCA (nothing installed?)
│   └── placehld
│       └── ... NCA
└── save
    ├── 8000000000000000
    └── 8000000000000120

On a v2.1 system with MountBis, the only thing under here is "PRF2SAFE.RCV".