Minecraft Forums

Quote from magickitty »

the frame rates in that world VS what I get in normal worlds is massively slow. windows xp sp3 and that was a old save from around halloween time. it was giving me 1fps all the time. 32 bit and my specs are dual core amd with a decent video card 3g ram. usual frame rate while fraps encoding is stable @ 29fps.

I deleted the nether (yes it was that bad) and regenerated it. Your portal is not in the same place but it is no longer corrupted. Maybe it was because you were using hax? (infinite armor/health = hack)

Here is a link to the world

Quote from Heaney555 »

Hey man, I hope you can help.

My world is corrupt -.-

Here is the world folder (zipped): http://www.mediafire.com/?urtyp5mg0pfjfly

I will freaking love you so much if you can fix this!!!

Do you have any backups? Just one at any point will be sufficient. The metadata file seems corrupted, if I replace it with an older one it should be fine. The world should also still be exactly the same.
Some servers make frequent backups. If you ever made a copy of the save at any time, that will be sufficient. See the instructions in the second post about how to upload world metadata.

The problem seems to be that the metadata file for the world as it exists in the zip is completely blank. Nothing in it at all. If you can get an older copy of it, I can probably fix everything.

In the event that you don't have one, I could probably make something work, but you will probably get terrain mismatch errors if you expand further.

Is it an old save? Saves created before the halloween update didn't like to properly keep track of the save size.

Have you modified it, like with MCEdit? I have noticed that modifying a save can break the size estimate.

If its that big of an issue, you can upload the metadata file and i'll look at it. Check the second post for instructions if you need them.

A Brief Description of the Format
A world exists as a folder with a bunch of stuff in it. A very basic world contains the following things:

files:
level.dat
level.dat_old
session.lock
region files

level.dat is the most important part of the world. I refer to it as the world metadata or level metadata. It contains the map seed, the player inventory, position, spawn, and other such important things. When you click the [single player] button, minecraft checks the world metadata in each of its 5 save folders. If the metadata doesn't exist or is unreadable, minecraft displays that world as an empty world.

If the level metadata is corrupted, it can be restored from the backup, level.dat_old. This does not (as far as I know) happen automatically, and if you try to create a new world in the slot of a corrupted existing one, THE METADATA BACKUP WILL BE OVERWRITTEN AND LOST FOREVER. The inventory, location, spawn, etc... can be easily replaced, but once the map seed is lost, it is impossible to get it back. This is another reason why it is important to make sure that you back up every world you care about AT LEAST ONCE. Even if it is a very early backup right after you create it. That backup can be used to restore the map seed.

Session.lock is not important.

Chunks are stored in region files as of beta 1.3. Region files are a solution to what was a very inefficient way of keeping track of the save data. Each region file can hold up to 1024 chunks in a 32x32 square. chunks are anchored to sector boundries within the region files, but otherwise are free to move around, and are not in any order inside a region file. the first and second sectors are dedicated to indexing the chunks within the region file. Chunks can be compressed either with gzip or with the faster deflate, to save time.

Data can become corrupted in a number of ways. By far the most frequent is due to the client or computer crashing. Since the client is almost constantly updating the world metadata (which, for some reason, is gzip compressed), this file is very prone to corruption. Chunks are vulnerable too. Numerous kinds of chunk corruption exist. Usually, saving of the chunk will be cut off part way, causing the archive to break. Depending on how far into the file minecraft got before failing, damage can range anywhere from simply resaving the chunk to crashing the client when it is loaded and requiring deletion. Most kinds of chunk corruption only affect the chunk, and not the entire region file. Sometimes, more serious error occur if the crash occurs between when the index updates and when a chunk is saved, causing referencing errors. A chunk may be referenced in the wrong place, or may stop being referenced entirely, or you may end up with a reference that points to nothing.

The tool I am creating will:
1. verify that the metadata archive is complete. If it is, it will overwrite the backup with a current version, and make a second backup just in case. If it is not, it will attempt to read as much as possible from the archive, and then merge anything it can save into the backup and restore it (first backing it up, in case it fails)
2. if the archive test succeeds, it will open the archive and check that everything is present and that everything makes sense.
3. it will test every archived chunk. If it finds one that fails the test, it will attempt to read as much as possible from it, and recreate as much of it as possible.
4. it will check the contents of every chunk, making sure that no internal corruption exists and that everything is in order. In the event that something is missing, it will regenerate it as best it can.
5. if a chunk is beyond repair, it will back it up and remove it.

How to upload a save

For SSP players -

[*:21b27vgz]Use your file browser to navigate to the following location:
Windows:


%appdata%\.minecraft\saves


Mac:


/Users/<username>/Library/Application Support/minecraft/saves


replace <username> with your username.
Linux and most others:


~/.minecraft/saves


[*:21b27vgz]Compress the save you are having trouble with into a zip file. If you need help with this, use [url=http://google.com]Google.[/url]
[*:21b27vgz]Please give the compressed world a name WITH YOUR USERNAME IN IT. I deal with a lot of these, keeping them straight if they are all called 'world 1' is a real pain.
[*:21b27vgz]upload the zip to mediafire or megaupload or usaupload or filefactory or whatever website you use.
[*:21b27vgz]post a link to it with the [url] tag.

For SMP players -
Contact your server operator.

For SMP Server Operators -
Follow the instructions for SSP above, except post the server's save. Save locations differ depending on server software.
the default software (from the minecraft website) uses:

<serverpath>\world

I don't know about the others.

How to Upload Save Metadata
The save metadata is a file called level.dat that stores your inventory, your position, the level terrain generator seed, the world size, your spawn point, and some other important things.

[*:21b27vgz]use the instructions above to locate your save.
[*:21b27vgz]open the save folder. It should be full of folders and should have one file called level.dat .
[*:21b27vgz]zip and upload level.dat using the method in the instructions above.

some problems do not require the whole world to fix, and level.dat is usually a 1kb file, wheras the whole world may be dozens of megabytes.

How to Back up a Map
1. Find your map using the information above.
2. Compress the folder with the archive manager of your choice.
3. Put the archive in a safe place (and it might help to put the date in its filename to, eg. name it WorldX-Jan19-2011.zip so you can keep track of them better)
*Server software often makes automatic backups. Server Operators may wish to check if their server supports automatic backups and configure them.

How to Back up Save Metadata
1. Find your save using the information above.
2. Inside the save folder (worldX for SSP) find the file called "level.dat".
3. Make a copy of it called "backup.dat"
4. If you can't find one called "level.dat", it is probably showing up as just "level". Make a copy and name it "backup".

How and When to Merge a Save
You need to merge a save IF and ONLY IF I provide direct instructions to do so.
1. Extract the compressed partial save.
2. Drag and drop the partial save into the saves folder (where the original save already is)
3. Your operating should prompt that the folders will be merged, click ok.
The merge should move everything in the partial save into the existing save. Files present in both will be overwritten by the files in the partial save, otherwise files will remain unchanged.

How to Restore the Metadata Backup
1. open the saves folder, and open the corrupted world.
2. find the metadata file (level.dat) and rename it to level.dat_broken
3. find the metadata backup (level.dat_old) and rename it to level.dat
If minecraft still doesn't recognize the world and you have a backup, either of the whole world or just the metadata
4. undo step 3
5. copy the metadata from your backup and put it in the world folder. name it level.dat

http://www.minecraft.net/haspaid.jsp?user=Raziel

Have you bought the game? What is your username?

Otherwise, this looks cool.

Not sure if srs...

OT: These foums kick ass now. They were bland before. This just looks epic.

Like you if you agr- ... No, no no... This isn't Youtube. Sorry, ya'll.

Notch said it looks ugly (at the moment), but regardless I'm still excited for a new realm. New portal materials?

However, I agree that Notch should have focused more on updating the Nether. There's only three exclusive materials you could gain from there. It needs minerals and that stuff.