Hi Folks,
Soak Test - Running a system at high load for a prolonged 
period of time. For example, running several times more 
transactions in an entire day (or night) than would be 
expected in a busy day, to identify and performance 
problems that appear after a large number of transactions 
have been executed. 

Objectives of Soak Testing

The objective of soak testing is to identify any 
performance problems that may appear after a system has 
been running at a high activity level for an extended 
period of time.

It is possible that a system may? Stop? Working after a 
certain number of transactions have been processed due to 
(for example): 
1.	Serious memory leaks that would eventually result 
in a memory crisis; 
2.	Failure to close connections between tiers of a 
multi-tiered system which could halt some or all modules of 
a system; 
3.	Failure to close database cursors under some 
conditions which could eventually result in the entire 
systems stalling; 
4.	Gradual degradation in response time of some 
function as internal data structures become less efficient 
during a long, high intensity test. 
Soak testing provides an opportunity to identify such 
defects.

I think it will help you out 

Regards,
Shankar

To identify memory leak problems for longer period

simply Soak esting is a combitation of load & endurance
testing. thr this we can identify the memory leaks of an
application.

ideyifying the memory leaks in application.

Soaktesting Nothing But Endurance test In This We Can find
out MTBF And MTTF

MTBF:Mean Time between Failure of application
MTTF:Mean Time To Failure