Source review: October 11, 2026. Follow the linked DSi Guide and DS-Homebrew documentation for your exact setup. Their supported installers and procedures can change.
Separate the backup types
A DSi NAND backup preserves internal console storage. An SD-card copy preserves photos, homebrew, settings and other files stored on that card. A game-card dump and its save are another pair of records. No single one of these replaces every other backup. Make a small inventory showing where each file came from, the date, tool release and intended use. Retain unmodified originals and work with copies when testing emulators or extracting individual files.
Make the NAND dump before permanent changes
The DSi Guide uses dumpTool to read internal storage and recommends at least 250 MB free on the SD card. After a successful dump it produces a DT-prefixed folder containing nand.bin and nand.bin.sha1. Copy the entire output folder to more than one separate storage device and confirm the copies can be read. Keep the console identity associated with the archive privately. A backup from another DSi is not a substitute for the original unit's recovery image.
Understand the checksum caveat
dumpTool calculates its SHA-1 before appending the no$gba footer, so hashing the final nand.bin as a whole does not match the supplied nand.bin.sha1. The guide documents this distinction and a method to create a footer-free copy. Do not conclude that every difference is harmless: distinguish this known format behavior from a truncated transfer or changed file. Preserve the original dump and compute an additional checksum of that complete original for checking future copies, clearly labeling which checksum applies to which representation.
Preserve game-card and installed-title data
GodMode9i documents cartridge dumping and save operations for supported hardware arrangements. Follow its DSi-specific instructions and verify which storage device receives the output. For DSiWare, the DSi Guide uses GodMode9i's title manager when the SD and NAND are mounted; output is placed in the gm9i/out directory. Keep application data and saves together with identifiers that make them recognizable later. Successful extraction is not evidence that a file can be installed on a different console or that every loader supports it.
Test the archive without rewriting the console
Check file sizes, checksums and readable copies before treating the archive as complete. Where the recovery documentation specifies an emulator validation, use a copy and retain the original unchanged. Avoid restoring NAND simply to prove that a backup exists. A restore writes internal storage and belongs to a separate last-resort workflow. For ordinary save migration, verify the copied save in the intended game or documented loader, and keep the old save until the result is confirmed. Reliable preservation combines several distinct backups, a tested copy process and enough notes to identify the right file later.
Sources and project documentation
- DSi Guide: NAND backup and footer caveat
- DS-Homebrew: GodMode9i features and source
- DSi Guide: installed DSiWare extraction
Before restoring anything, read recovery and hardware triage.