Advice sought RE Input/output errors during backup attempt
Recently I was trying to do my (far too infrequent) full system backup.
I was using sdvdbackup (part of the scdbackup package). Halfway through one disc, the program reported a read error accessing a file in /sys/devices/pci0000:00/0000:<something>/<something> (Sorry, I can't be more precise. I'm not at my machine right now, but I don't think the specific file matters for this question.) The backup then failed.
I tried explicitly excluding the offending file, but hit another read error on the next file in the directory.
Exitting the backup program, I tried to "cat" these files. I recieved several input/output errors. Uh-oh.
I don't know too much about this corner of the linux directory tree, and I need some advice:
Should I delete the problem files and replace them with copies from my last backup? I don't think I've installed any new PCI devices since that backup; only a new second HDD.
How likely is it that there is physical damage to my disc? How can I check?
Should a disc that has suffered some damage be replaced at once, or might there be a long interval before further damage? Can the damaged area be "cordoned off" in some way?
Is there another way to repair damage that might be better than a restore from backups?
I know that's a lot of questions. All thoughts are welcome. Being denied a successful backup has really underscored its urgency for me. Thanks for your help!
Do not backup /sys and /proc. And, assuming you have a modern system using udev or devfs, do not backup /dev.
/sys and /proc do not contain real files, but are actually hooks into the kernel represented as a filesystem. In other words, the kernel exports data through these dynamically.
To modify the advice given by Matir, if your backup utility allows you to prune the directories (i.e. preserve the directory structure, but not the files within), then do so. You won't have to recreate the directories manually later.
I use DAR for my backups, which has excellent filtering for just that purpose. I've tried Kdar, but it seems to lack the full functionality of the command-line DAR. DAR lends itself to the creation of a script to include all that you want it to do in re backups, what to compress or not compress, what to exclude, what directory tree to preserve but not the files within, and much more.
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