In a standard archive, files are compressed individually. In a archive, all uncompressed files are concatenated and treated as a single large data block . Solid Archive Non-Solid (Standard) Compression Ratio Higher (best for many similar files) Lower Extraction Speed Slower for single files (must decode preceding data) Faster (direct access to any file) Reliability Lower (one error can corrupt the whole block) Higher (corruption usually only affects one file) Modifiability Difficult (adding/deleting requires re-compressing) Easy (files can be updated individually) Dealing with .005 Files
The identifier refers to the 5th part of a multi-volume 7-Zip archive. The Solid feature mentioned is a specific compression method used within these archives to achieve higher compression ratios. Understanding Solid Compression 3s.7z.005
: You only need to open the file ending in .001 ; 7-Zip will automatically detect and join the rest. In a standard archive, files are compressed individually