Thanks ifitaintboeing
,
My take on the subject is that you need to maintain a hard copy logbook, and you can only use an electronic one as a backup.
If the dog eats your logbook then if you need to prove such things as "Biennial Training Flight" or "3 Landings/Take-offs in last 90 Days", then its a case of going back to the instructor or airfield to get a copy of their records.