4 ms·

Confirming this, and confirming that the recovery record (that I had set to a hefty 10%, I think, because the data was important to me) did let me recover archi

Confirming this, and confirming that the recovery record (that I had set to a hefty 10%, I think, because the data was important to me) did let me recover archives that suffered physical media damage, which would have been irrecoverable had I used something else. I wish 7zip had this feature. This was one of the most satisfying progress bars: from "your data is dead" to a few minutes later "Successfully recovered full data from recovery record" :))))) I anticipate passerbys might say "but you can do the same with TAR + xyz + abc". To this I’ll reply: 1. The nice thing about RAR is that this recovery feature has been built-in and extremely easy to use, since the 90s. 2. Usability nit aside, I'd love to hear about alternatives.

computator 5y ago
> let me recover archives that suffered physical media damage > Usability nit aside, I'd love to hear about alternatives. Make two or more copies on different media. Sure, RAR or another archiver can save you from partial media damage but nothing saves you from total media damage other than having completely separate backups.
- nine_k 5y ago
  Two copies is 200%, the redundancy records are normally below 110%. It's like RAID1 vs RAID5, only without the speed bonus of RAID1.
  - ronjouch 5y ago
    Yeah. They have a point, though, more copies is good too. To me it's a case of “why not both?”, and I remain interested in software free RAR alternatives with a RecoveryRecord-ish feature.
btdmaster 5y ago
Par2 is always an option, and RAR implements Reed-Solomon error correcting codes and there are many recent implementations of those: https://github.com/klauspost/reedsolomon https://github.com/klauspost/reedsolomon.
- ronjouch 5y ago
  I'm sure there is a public algorithm / implementation. My question here is: is there an existing archive format (like .7z) that integrates it to the archive format and knows to update the error-correction data on archive update? Maybe not in a way that is as user-friendly as RAR, but "halfway there". Or are you suggesting all my .7z files should come with a sibling .par2, that I must remember to regenerate after every change of the .7z ? I know I was asking here about "Usability-aside alternatives", but that alternative seems quite inconvenient and below the bar I was ready to accept when asking for less-user-friendly stuff.
  - ronjouch 5y ago
    A by-the-way note for passerbys on the subject of PAR recovery records: - As usually, the Arch wiki has an excellent page on the topic: https://wiki.archlinux.org/title/Parchive https://wiki.archlinux.org/title/Parchive - Hey, par3 is in the works: https://github.com/Parchive/par3cmdline/issues/1 https://github.com/Parchive/par3cmdline/issues/1 - I created [Feature request / par2create] Option to regenerate par2 files if input file changed : https://github.com/Parchive/par2cmdline/issues/170 https://github.com/Parchive/par2cmdline/issues/170
- ASalazarMX 5y ago
  > Reed-Solomon error correcting codes Had to double check that. I would have sworn those codes were called Solomon-Reed, not Reed-Solomon. Guess I have my little Mandela Effect now!

computator 5y ago

> let me recover archives that suffered physical media damage > Usability nit aside, I'd love to hear about alternatives. Make two or more copies on different media. Sure, RAR or another archiver can save you from partial media damage but nothing saves you from total media damage other than having completely separate backups.

nine_k 5y ago
Two copies is 200%, the redundancy records are normally below 110%. It's like RAID1 vs RAID5, only without the speed bonus of RAID1.
- ronjouch 5y ago
  Yeah. They have a point, though, more copies is good too. To me it's a case of “why not both?”, and I remain interested in software free RAR alternatives with a RecoveryRecord-ish feature.

btdmaster 5y ago

Par2 is always an option, and RAR implements Reed-Solomon error correcting codes and there are many recent implementations of those: https://github.com/klauspost/reedsolomon https://github.com/klauspost/reedsolomon.

ronjouch 5y ago
I'm sure there is a public algorithm / implementation. My question here is: is there an existing archive format (like .7z) that integrates it to the archive format and knows to update the error-correction data on archive update? Maybe not in a way that is as user-friendly as RAR, but "halfway there". Or are you suggesting all my .7z files should come with a sibling .par2, that I must remember to regenerate after every change of the .7z ? I know I was asking here about "Usability-aside alternatives", but that alternative seems quite inconvenient and below the bar I was ready to accept when asking for less-user-friendly stuff.
- ronjouch 5y ago
  A by-the-way note for passerbys on the subject of PAR recovery records: - As usually, the Arch wiki has an excellent page on the topic: https://wiki.archlinux.org/title/Parchive https://wiki.archlinux.org/title/Parchive - Hey, par3 is in the works: https://github.com/Parchive/par3cmdline/issues/1 https://github.com/Parchive/par3cmdline/issues/1 - I created [Feature request / par2create] Option to regenerate par2 files if input file changed : https://github.com/Parchive/par2cmdline/issues/170 https://github.com/Parchive/par2cmdline/issues/170
ASalazarMX 5y ago
> Reed-Solomon error correcting codes Had to double check that. I would have sworn those codes were called Solomon-Reed, not Reed-Solomon. Guess I have my little Mandela Effect now!