Residual bugs in mature systems can be classified into two main categories .Heisenbugs tend to be more prevalent in distributed systems than in local systems.
The more things I can do with you, the more things I have to think about recovering from.
 Handling failures is an important theme in distributed systems design.
To be truly reliable, a distributed system must have the following characteristics: These are high standards, which are challenging to achieve.
Probably the most difficult challenge is a distributed system must be able to continue operating correctly even when components fail.
" Common sense would be to answer, "Never." That is an infinitely large number in human terms. If I send a message to you and then a network failure occurs, there are two possible outcomes.