One advantage of this usb import approach is that it can in certain cases be used to recover a corrupted SD card were a previous backup archive was not made - or is quite old. If the SD card mounts ok the script may run without trouble, but if the damage is greater, running the file system consistency check utility (fsck) maybe needed before doing an import.
Both Glyn and I had our home systems go down following the same power cut in our village last weekend. While my system booted there were issues with emonhub and redis resulting from SD card corruption. I was able to recover using the importer tool without running fsck. Glyn’s on the other hand would not boot initially - but after running fsck we were able to mount the old SD card and run the import script.
Here are the steps to do this:
1. Insert SD card in SD card reader and plug in to the emonPi/emonbase/raspberrypi running a fresh copy of the emonSD image.
2. Attempt to recover the SD card partitions e.g:
sudo fsck.ext4 /dev/sda2 (root OS partition)
sudo fsck.ext2 /dev/sda3 (data partition)
3. Once complete, run the importer tool as above.