Recently I used 7-Zip to compress a number of folders so I could transfer them to a different computer. Most of them worked fine but one 7z file refuses to be moved from the portable disc I saved it on.
When I try to move it from the portable disc, I get this error: "Cannot copy Heard Music: Data error(cyclic redundancy check)." and the process cancels itself.
I tried to extract the file from where it is and was able to recover about 1/3 of the data, but I still get a cyclic redundancy error right before the process halts.
Is there any way I can get my data back? Or at least skip over whatever is causing the problem and retrieve the rest?
UNSOLID archive: The 1 file is lost. But all other files
SOLID archive: This file and all folowing (sortorder ?
Windows BUG - not defined :-( ) are lost. Recovery
"cyclic redundancy" usually means that the CD/floppy/... is scratched or something.
To specify what stated above, solid archive are stored as a single stream, so you must have the previous data to uncompress the following; so according to what you (OP) said, you would loose 2/3 of the archive.
If on the other hand, your archive is not solid, you will have to extract all files except the one(s) on which the extraction fails, and you will loose only these files.
By default there is limitation for solid block size:
Compression Level Solid block size
Fast 16 MB
Normal 256 MB
Maximum 1 GB
Ultra 4 GB
Limitation for solid block size usually decreases compression ratio but gives the following advantages:
Decreases losses in case of future archive's damaging.
Decreases extracting time of the group of files (it can be one file), if this group doesn't contain all files of archive.
Current version of 7-Zip doesn't support updating for solid archives, if it requires repacking solid blocks.
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