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Even with ddrescue you might lose a few bits. You will only find out when accessing those specific files and bits. For my photo history I prefer to keep PAR fi
by mpol 4y ago
Even with ddrescue you might lose a few bits. You will only find out when accessing those specific files and bits.
For my photo history I prefer to keep PAR files next to it. On a running mechanical disc I haven't seen issues when running the repair. I do expect to see some errors in the future and as long as it stays under a certain percentage, things will be fixable.
I started doing this long time in the past, when harddisks were awful. I would often lose mp3 files due to damage. With mp3 you can easily hear it. With jpeg images you can often see damage as well.
- mrjin 4y agoNot much point, way too time consuming. I dumped hundreds of CDs/DVDs as most of them were unreadable. 20% of them might still good, but really no longer had that energy to savage them.
- necheffa 4y agoIf you pay attention to the ddrescue output it is pretty obvious when you are missing a few bytes here and there. I have long since moved away from optical media, really for anything, but especially archival. Long term storage to me looks like an array of magnetic disks held together with ZFS.
- acomjean 4y agoCould you explain the PAR file and why that would help?
- loeg 4y agoPAR files are a form of Forward Error Correction (FEC) (implemented with Reed Solomon). They can be used to repair some percentage of damaged blocks in a file or set of files. The percentage is determined ahead of time when you generate the FEC (PAR files) and imposes the same amount of storage overhead (i.e., 15% redundancy costs 15% additional disk space with Reed-Solomon). https://en.wikipedia.org/wiki/Error_correction_code#Forward_error_correction https://en.wikipedia.org/wiki/Error_correction_code#Forward_... https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon_error_correction https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon_error_cor...