Best way to safely host a high volume online transactional wallet? I am looking at starting a business that will send and receive a large amount Bitcoins in a semi automated manner using API's. I was wondering what is the best way to do do this in a secure way to limit my exposure to hacking? My initial thoughts are as follows:

1) Clearing Wallet: have a clearing wallet that holds say 10% over my expected daily amount of bitcoins that will be used for sending and receiving bitcoins. Any time this wallet contains more than my 10% configured amount, a bot will move the excess bitcoins to another offline wallet.

This wallet will be backed up on 3 USB drives using double encryption and be hosted at blockchain.info (two factor authentication will be used to access this wallet at blockchain.info)

2) Emergency Paper Wallet: This is a paper wallet and will be used to hold an additional days worth of bitcoins. If for any reason I need to top up my Clearing Wallet this will be used and then discarded. (one time use only)

3) Cold Storage Wallet: This is were the excess coins from my clearing wallet will be forwarded to and keep offline. This wallet will be created using a bootable USB/CD OS to ensure the machine it is created on is not compromised. This wallet will then be used to make a number of Emergency Paper wallets that will be used to top up the clearing wallet if funds are ever running low. (this wallet will only ever be accessed using a fresh bootable OS)

Is this a good way of ensuring I have a low exposure to being hacked or is there a better way of doing this?
It seems to be a good approach. The fundamental is keep a little bit "hot" to high liquidity and keep the rest into USB stickers + papers and if possible keep it safe in a vault or bank. Also, keep the anonymity and security of who has the access to the Bitcoins. Remember: Bitcoin is real money, and if you are working with a lot of money, it can be dangerous, someone can try to extort you to reveal all secret.

Don't forget too that USB stickers are volatile in long term by definition, and are not 100% safe. CD and DVD can scratch or can degrade over time. So, the paper is fundamental; keep it in a clean and dry place. Remember also to generate the wallet keys in a offline computer (installed from zero if possible). Read this article: How to set up a secure offline savings wallet.



There is a nice article about it here: Coinbase now storing 87% of customer funds offline