Flash Filesystem

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NAND structure

The Switch's eMMC storage features a large user area, two smaller boot partitions, and a replay-protected memory block which is unused (no authentication key is programmed).

Boot Partitions

Boot Partition 0 (0 of 1)

Offset Size Description
0x000000 0x4000 Title 0100000000000819 BCT
0x004000 0x4000 Title 010000000000081A BCT
0x008000 0x4000 Title 0100000000000819 BCT
0x00C000 0x4000 Title 010000000000081A BCT
0x010000 0xF0000 60 additional BCTs, normally unused/empty on retail systems.
0x100000 0x40000 Title 0100000000000819 "package1"
0x140000 0x40000 Title 0100000000000819 "package1" (Backup)
0x180000 0x4000 Keyblob area
0x184000 0x20 Unknown pseudorandom data, often changes on reboot. All zero on 1.0.
0x184020 0x8? Increments on every boot until hitting a certain number? Bottom 10 bits (0x3FF) are always zero. All zero on 1.0.

Boot Partition 1 (1 of 1)

Offset Size Description
0x000000 0x40000 Title 010000000000081A "package1"
0x040000 0x40000 Title 010000000000081A "package1" (Backup)
0x080000 0x40000
0x0C0000 0x40000


Starting at offset 0x180000 is an array of 0x200-byte entries, for a total of 32 keyblobs. Each one is unique compared to the others and they are all console unique.

From each 0x200-byte entry only the first 0xB0 bytes effectively form the keyblob as below.

Offset Size Description
0x0 0x10 Keyblob AES-CMAC over the next 0xA0 bytes (safe against timing attacks)
0x10 0x10 Keyblob AES CTR
0x20 0x90 Keyblob encrypted payload
0xB0 0x150 Unused, all-zero.

The active bootloader's version (offset 0x2330 in the BCT) acts as an index to control which keyblob should be installed into the system. NS uses this during system updates to install the keyblob into the customer data section in BCTs (offset 0x450).

Boot also uses this index for repairing corrupt sectors.

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. The official name for this partitionID from SystemInitializer is "nn::fs::BisPartitionId::UserDataRoot".
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" in firmware package A (0100000000000819) by default. With the exFAT update installed, this is switched to firmware package C (010000000000081B). The data stored here matches the raw /nx/package2 file stored in the 81[9AB] data archives -- there is no additional encryption. "BCPKG2" is "BootConfigAndPackage2": for example, from SystemInitializer: "BootConfigAndPackage2Part1".
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 Installed at the factory, never written afterwards on retail. In one case this is identical to normal 1.0.0 pkg2, except this has encrypted data at the end padded for 0x1000-byte alignment.
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?) 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.

If the client process lacks the relevant permission for any of the above partition IDs, error 0x2EE202 is returned.

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

The filenames for saveimages is just "<lower-case hex u64 saveID>". SYSTEM-partition saveIDs are specified by FS commands, while USER-partition saveIDs are determined by FS-module internally. The high u32 of the saveID is normally either 0x00000000 or 0x80000000.


├── 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


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


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

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


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

The saves for all non-system applications, regardless of where the application is located(storageID), is stored here. Each user account which has savedata has a separate saveimage. Save-common for an application is presumably a separate saveimage too. Every saveimage here is only for applications.


├── 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".

System Savegames

This is a listing of known System Savedata and what titles they correspond to.

SaveID Owner Mount Notes
0x8000000000000010 account account:/ Account database.
0x8000000000000011 account idgen:/
0x8000000000000020 nfc data:/ NFC data and backups.
0x8000000000000030 ns mii:/ Mii database.
0x8000000000000031 ns mii:/ Mii test mode database.
0x8000000000000040 ns apprecdb:/
0x8000000000000041 ns nsaccache:/ Home menu icondata/lru list for recently played games.
0x8000000000000043 ns ns_appman:/
0x8000000000000044 ns ns_sysup:/ Content update context.
0x8000000000000045 ns vmdb:/ Version List/Required Version List storage.
0x8000000000000046 ns dtlman:/
0x8000000000000047 ns ns_exfat:/
0x8000000000000048 ns ns_systemseed:/
0x8000000000000050 settings SystemSettings:/
0x8000000000000051 settings FwdbgSettingsS:/
0x8000000000000052 settings PrivateSettings:/
0x8000000000000053 settings DeviceSettings:/
0x8000000000000054 settings ApplnSettings:/
0x8000000000000060 ssl SslSave:/
0x8000000000000070 nim nim_sys:/
0x8000000000000071 nim nim_net:/
0x8000000000000072 nim nim_tmp:/
0x8000000000000073 nim nim_dac:/
0x8000000000000074 nim nim_delta:/
0x8000000000000075 nim nim_vac:/
0x8000000000000080 friends friends:/
0x8000000000000081 friends friends-sys:/
0x8000000000000082 friends friends-image:/
0x8000000000000090 bcat news:/ Actual news msgpack archives.
0x8000000000000091 bcat news-sys:/ News metadata, tasklist, history, database, required system version, etc.
0x8000000000000092 bcat news-dl:/ Storage for newly(?) downloaded news list/data.
0x80000000000000A0 bcat prepo-sys:/ Play Report system information.
0x80000000000000A1 bcat prepo:/ Play Report msgpack archives.
0x80000000000000B0 bsdsockets nsdsave:/ Socket configuration saved data.
0x80000000000000C1 bcat bcat-sys:/
0x80000000000000C2 bcat bcat-dl:/
0x80000000000000D1 erpt save:/ Contains "/journal" report listing + actual crash reports ("/%08x-%04x-%04x-%02x%02x-%04x%08x"), which are serialized via MsgPack.
0x80000000000000E0 es escertificate:/
0x80000000000000E1 es escommon:/
0x80000000000000E2 es espersonalized:/
0x80000000000000F0 ns pdm:/ Play Data log.
0x8000000000000100 pctl pctlss:/ Parental Control settings.
0x8000000000000110 npns npns_save:/ Push notifications persistent storage.
0x8000000000000120 ncm  ? meta/imkvdb.arc for system partition. Cache of data extracted from the .cnmt for installed titles?(Including 816)
0x8000000000000121 ncm  ? meta/imkvdb.arc for sd partition. In some cases this save only contains a "meta/" directory without any file.