Hacking Shrink your sysNAND backup ...

[Escape1975]

I have figured out the following steps to shrinking your sysNAND backup without altering any info ...

1) Open your sysNAND backup in NxNandManager
2) go to SYSTEM, then Advanced Save, use "Crypto: none", "Passthrough zeros: yes", and Dump.
3) go to USER, repeat same procedure.
4) Now open sysNAND backup in HacDiskMount
5) go to SYSTEM, don't enter any keys, restore from file and pick the exported file from step 2.
6) go to USER, same as before, except pick file from step 3.
7) You can now mount the partitions as read only to test if the files are there ...

Now if you compress your backup it should be much smaller ... (mine went from 29 GB to 1.4 GB)
I would advise against ever formatting the SYSTEM or USER partitions in Windows as it messes them up.

You could further reduce it by removing files that are not needed, but most likely
that will cause red flags as the system will show up more clean that it should when online ...

 

[Draxzelex]

Shrinking eMMC backups isn't anything noteworthy or relevant since we've been doing it ever since the eMMC could be dumped all the way back in 2018 as seen here. And if you think about it, shrinking the backup is not that useful since you need the space to uncompress it anyway. The only scenario where I would imagine it being useful is if you are really running low on space but in that case, the better solution would to be to delete anything you don't need that is taking up a lot of space.

 

[The Real Jdbye]

Of course this only works if you haven't filled up your sysNAND with games.

 

[Escape1975]

Shrinking eMMC backups isn't anything noteworthy or relevant since we've been doing it ever since the eMMC could be dumped all the way back in 2018 as seen here. And if you think about it, shrinking the backup is not that useful since you need the space to uncompress it anyway. The only scenario where I would imagine it being useful is if you are really running low on space but in that case, the better solution would to be to delete anything you don't need that is taking up a lot of space.

I get it, but also note that the instructions provided in that thread say to format the partitions from windows,-
well this causes irreversible changes to OEM partitions that can never be recovered and whether nintendo
will be able to tell that they have been altered is another question, but they will be completely different,
even down to parameters such as number of heads defined in the fat32 header, adding boot sectors, etc.

It also will destroy some encrypted data in sectors 2,3,4,5 just between fat32 primary and backup sectors,
which is stored at 0,1 and backup at 6,7 but as to what it contains nobody seems to know as I've asked before

--------------------- MERGED ---------------------------

Of course this only works if you haven't filled up your sysNAND with games.

That is correct, and even if you reset your switch your backup will contains all these deleted files on it ...

 

[Draxzelex]

I get it, but also note that the instructions provided in that thread say to format the partitions from windows,-
well this causes irreversible changes to OEM partitions that can never be recovered and whether nintendo
will be able to tell that they have been altered is another question, but they will be completely different,
even down to parameters such as number of heads defined in the fat32 header, adding boot sectors, etc.

It also will destroy some encrypted data in sectors 2,3,4,5 just between fat32 primary and backup sectors,
which is stored at 0,1 and backup at 6,7 but as to what it contains nobody seems to know as I've asked before

Then I hope you realize that the situation you are providing is highly niche and as explained earlier, practically shrinking eMMC backups is not that useful. Another thing to note is that this does nothing to those who have used a lot of their internal storage. Take it is as some friendly advice that nobody else commented or praised your idea since you posted it.

 

[Escape1975]

Then I hope you realize that the situation you are providing is highly niche and as explained earlier, practically shrinking eMMC backups is not that useful. Another thing to note is that this does nothing to those who have used a lot of their internal storage. Take it is as some friendly advice that nobody else commented or praised your idea since you posted it.

It is, but I'm not forcing anyone to do anything with the information provided.

The shrinking should happen whether or not the space was once completely filled up, so for example
if a backup was done shortly after a reset then this will shrink it quite considerably, about 15 fold,
as it will only export the unused portions. If someone backs it up while having 20 gigs of data
stored in their storage then of course this won't really do much ...

Whenever I modify or follow guides I like to gain an understanding of most of the things that are being done,
and in this case I found it interesting that something like this can be achieved, without following the earlier
re-format from windows advice, which I would recommend not to follow as I've done myself

I had a tough time recovering my original nand backup that I no longer had, and I stumbled at the data in sectors 2-5 ...

That's all

 

[nilisco]

It is, but I'm not forcing anyone to do anything with the information provided.

The shrinking should happen whether or not the space was once completely filled up, so for example
if a backup was done shortly after a reset then this will shrink it quite considerably, about 15 fold,
as it will only export the unused portions. If someone backs it up while having 20 gigs of data
stored in their storage then of course this won't really do much ...

Whenever I modify or follow guides I like to gain an understanding of most of the things that are being done,
and in this case I found it interesting that something like this can be achieved, without following the earlier
re-format from windows advice, which I would recommend not to follow as I've done myself

I had a tough time recovering my original nand backup that I no longer had, and I stumbled at the data in sectors 2-5 ...

That's all

Thank you. Was looking for info on how to compress my sysnand and finally found this. Searching for this leads to thousands of useless results on reddit/gbatemp.

 

[Maupiti]

Thank you. Was looking for info on how to compress my sysnand and finally found this. Searching for this leads to thousands of useless results on reddit/gbatemp.

What’s the « point » of shrinking sysnand ? EmuMMC /Emunand I can understand, but sysnand ? The size of the backup. ?

The « road » I went, since I bought my switch Erista unpatched in early 2018 was to stick with EmuMMC /Emunand .
Leaving the sysnand untouched. This first backup is well preserved and full, not shrinked.

I did shrinked an Emunand Sxos setting my dual boot with atmosphere (full EmuMMC).

 

[nilisco]

Again, thanks for the guide on how to actually do this instead of every rando posting WHY U DO THIS?

 

[Maupiti]

Again, thanks for the guide on how to actually do this instead of every rando posting WHY U DO THIS?

Good you find a guide to lead you where you wanted, but may I ask you why ?

 

[Deleted member 569438]

Love it. This is super useful for just keeping at least one "oh fuck" emergency backup on the cloud just in case all of your local backups were lost.

32 GB is a lot and most cloud storage options don't let you upload this much stuff without paying for additional storage, but if you can compress your backup to 1.4 GB then you can upload that to the cloud and at least you'll have something even if you were to lose all of your local backups. That's the point.

Full backup on my hard drive, full backup on a 32 GB flash drive, compressed backup on the cloud. If I lose the backup on my hard drive I can recover with the one on my flash drive, but if in an emergency the flash drive backup is also lost, I'll at least have a compressed backup on the cloud that'll always be there.

 

[Maupiti]

Love it. This is super useful for just keeping at least one "oh fuck" emergency backup on the cloud just in case all of your local backups were lost.

32 GB is a lot and most cloud storage options don't let you upload this much stuff without paying for additional storage, but if you can compress your backup to 1.4 GB then you can upload that to the cloud and at least you'll have something even if you were to lose all of your local backups. That's the point.

Full backup on my hard drive, full backup on a 32 GB flash drive, compressed backup on the cloud. If I lose the backup on my hard drive I can recover with the one on my flash drive, but if in an emergency the flash drive backup is also lost, I'll at least have a compressed backup on the cloud that'll always be there.

That’s what I thought, thanks for clarifying.