Mainly because this is a Public Forum and the Banking Industry tend to want to keep this all In House so that members of the Public don't know just how weak their systems actually are.
Well banks tend to have Redundant Data Centers so that if one is hit in one area they can switch to another not affected by the local conditions like Fire, Flood, Famine. That is the basis of all Banks DR plans at least so that if something goes wrong at one place they are up and ruining in minutes with only a small Data Loss that needs to be reentered. For some strange reason people get upset when they can not get to their money or credit.
At every Data Center they tend to have several Redundant systems so that if one gets infected with something or suffers a Hardware failure they can use another system and rebuild the affected system/s while continuing to work. So depending on the size of the bank they would have 3 or more redundant systems and one that can be used but remains isolated from outside interference so that would kill off Internet Banking and the like, then if that particular Data Center is affected by some local inclement conditions they can just switch services to another Data Center and continue to operate without interruption.
The Bigger Data Centers who hold all of a States or Major Areas Data are then synced into bigger State or Federal Data Centers where the daily transactions are sent to at the close of trading or a couple of times a day depending on the services offered by the bank.
With all Bank DR Plans you really have to look at the Federal Legislation covering the Banks to see what is the Minimum Required Service Level that has to be maintained and then factor in a better offering so that the organization only ever gets below the Minimum Mandated Service Level in sever emergencies.
Col
