maximum value of n to be deadlock

Question

A computer system has 6 tape drives, with n processes competing for them. Each process may need 3 tape drives. What is the maximum value of n for which the system is guaranteed to be deadlock? Justify your answer.

Answer 1

the maximum value of n for which the system is guaranteed to be deadlock is 3 .

process * ( max need -1) = RESOURCES.  

n ( 3 - 1 ) = 6

2n = 6

n = 3

Hence at maximum we need 3  processes to be in deadlock .

Answer 2

try with hit and trial method

let if having two process

p1            p2

1              1

1              1

1              1

ie no deadlock

let if n=3 (ie. 3 process)

p1             p2             p3

1                1               1

1                1

1

here no deadlock(becoz after complition of p1 other will get chance)

but other case possible for n=3

p1              p2           p3

1                1              1

1                1              1

here u can see that deadlock is possible.(becoz we have to consider all possibility)

so n=3 for occurring deadlock

Comments

There is a better method than trial and error :) see my answer..