On Sun, Sep 03, 2017 at 11:35:25PM -0400, David Mitchell wrote: > I really do NOT remember running the --create command. There is no other explanation for it. It has happened somehow. > The pictures over 512k don't display correctly. So not only/necessarily a wrong data offset, but also wrong drive order. > At this point I'm hoping for help on next steps in recovery/troubleshooting. 1. Use overlays. https://raid.wiki.kernel.org/index.php/Recovering_a_failed_software_RAID#Making_the_harddisks_read-only_using_an_overlay_file That way you can safely experiment and create RAID with different settings. (Use --assume-clean and/or missing) 2. Check first 128M of each drive (your current data offset). See if you can find a valid filesystem header anywhere. That way you could determine the correct data offset. 3. Find a JPEG header (any known file type, like a 2-3M file) and look at the other drives for the same offset. You should be able to deduce RAID layout, chunksize, drive order from that. Instead of 3) you can also simply trial and error with overlays until you find a setting that allows photorec to find larger files intact. The resync might not necessarily have damaged your data. If the offsets were the same and the RAID level was the same, and the drives were in sync, a resync even with wrong settings would still produce the same data. For XOR, a ^ b = c and b ^ a = c so switching the drives does no damage provided you don't write anything else... Regards Andreas Klauer -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
