Backup
Making backups is not easy. You can backup your key, but to recover a disk failure (for example), you still need the channel state.
The problem is that if you announce an old channel state (after you recovered a backup), this is detected as Fraud and you might lose your funds.
Poor mans solution
Probably just take your wallet-file... See github for more info.
Hardware
If you’re putting a lot of money on your Lightning routing node, please use a reliable hard drives (with mirroring).
Data Loss Protection
Channel information
LND
For now, just backup the whole ~/.lnd directory.
Commitment revocation private key
Every commitment transaction has a unique commitment revocation private-key value that allows the other peer to spend all outputs immediately: revealing this key is how old commitment transactions are revoked. To support revocation, each output of the commitment transaction refers to the commitment revocation public key.