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scanning_fixing_levels

Scanning and Fixing Levels

RomVault defaults to Level 2 scanning and Level 2 fixing. These settings are best for almost all scenarios, however the options and use cases for the other levels are outlined below.


Scanning Level Settings

There are 3 different Scanning Level settings. The level set in the Global Settings controls the default behavior of the “Scan ROMs” button. Its possible to selectively scan with a different level by selecting what you want to scan in the tree then using the “Scan ROMs” top menu item.

Level 1Level 2 - DefaultLevel 3
DescriptionCursory ScanNormal ScanComplete Rescan
Hashing ScopeModified files since last scanModified files since last scanAll files
Hashing MethodZIP: read from header
7Z (non-solid or 1 file): read from header
7Z (solid with 2+ files): decompress and hash
CHD: read from header
Everything else: hash files
Decompress files and hashDecompress files and hash
- Size x x x
- CRC x x x
- MD5 x x
- SHA1 x x
SpeedFast if files are in archivesSlow for initial scanning
Fast for subsequent scans
Slow
Use CasesIf you haven't decided on a final place to store your ROMs yet or you just want to do a quick scan to join a torrentIts recommended to use the default Level 2 scanning in all situations unless you have a specific reason not toIf you suspect data corruption or you previously scanned with Level 1 and want to upgrade to Level 2 by hashing MD5 and SHA1

Note: RomVault has built-in header skipping logic that requires checking the first few bytes of a file to see if it has a header. Solid 7z archives with two or more files require decompressing in order to check for headers. For this reason its advised not to use Level 1 scanning for 7z archives, especially large archives. If you are going to need to decompress solid 7z archives anyways, it makes more sense to stick with a Level 2 scan which will also calculate the MD5 and SHA1.

Fixing Level Settings

There are also Level 1, 2 and 3 Fixing, which sort of works the same as Scanning Levels:

Level 1Level 2 - DefaultLevel 3
DescriptionCursory FixNormal FixComplete Rebuild
Fixing Method Fixes ROM sets by comparing the attributes below
- Size x x x
- CRC x x x
- MD5 x x
- SHA1 x x
Raw Copy*YesYesNo
SpeedFastFastSlow
Use CasesIf your ROMs are also Level 1 scanned and you want to do a quick fix before joining a torrent. There is no point in using Level 1 fixing with ROMs scanned with Level 2.Pretty much always use Level 2 fixing, especially if your ROMs are scanned with Level 2. This will ensure the highest accuracy and prevent hash collisions.Only useful if for some reason you want to rebuild archives from scratch and completely decompress and recompress all files in the archives every time.

Note: RomVault has the ability to copy files directly from a source to a destination archive without the need for recompressing as long as the archives are in TorrentZip format. This allows for extremely fast fix operations.

scanning_fixing_levels.txt · Last modified: 2020/12/15 15:30 by johnsanc