How do I backup my ether accounts?
To backup your wallet you will need to make a copy of the key file(s) located in your ethereum directory.
The file should look something like this:
I've suggested just saving the keystore contents, but you can of course backup the entire /ethereum directory; note, however, that this includes the chaindata files, and that's over 115 Gb, as of July 2018.
To import saved wallet files, simply copy them into the keystore directory of your system. Presale versions will end in the
*.jsonextension, but they will be recognized by the ethereum client.
To clarify, is it is the combination of your key file, and your knowledge of your password that constitutes your wallet. I just want to be absolutely certain before transferring Ether off exchange. That is to say with my key file and password, I could install Geth on a new computer, transfer my key file on a USB stick, and have access to my 'account'/Ether?
Yes for each key file, you need the password for it. Before deleting any key files, one should test the recovery process using small amounts of Ether.
So the only thing I need to save for a full backup of my wallets are the files in ~/.ethereum/keystore - is that correct?
@alper: To import/restore, copy the backed up files to the keystore of your (other) system.
@PaulPreibisch You also need a backup of each password for each file in ~/.ethereum/keystore
answer is not correct, on Mac the keystore is under `~/Library/Ethereum/keystore`
PLEASE MAKE SURE TO ALSO BACKUP YOUR PASSWORDS
Each key file (as described in @Ethan's answer) is encrypted and only usable with the correct password.
Another safety tip: Before deleting any key files, after you have done the backup, please try the import/restore process on another system to make sure you can send a small amount of Ether. (To import, copy the backed up files to the keystore of the other system.) When you can spend that small amount of Ether, that will give you more confidence that your backup actually works.