Deadlock: Safe or Unsafe

Question

Consider a system with 12 tape drives with:

Process	Max Need	Allocated
P1	10	5
P2	9	3

Is this system is in a safe or unsafe state? If it is not safe then under which condition system leads to deadlock?

Comments

I want to know that somewhere I have read that in the unsafe state if any further request made by any process then the system will move towards deadlock state from unsafe state.

Can you provide such a situation from above example or you may provide your own example.

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yes, it is true, in unsafe state if process request further resources without freeing its already captured resource then the system will go toward deadlock.

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Definitely Not in Safe State Because None Of Request Will satisfied By Remaining Avaliable Resources.

Answer 1

System has 12 tape drivers

process	max requirement	allocate	available	remaining
P1	10	5	4	5
P2	9	3		6

total available = 12-(5+3)=4

So, total available tape drivers are 4 and remaining requirements of P₁ and P₂ are 5 and 6 . This implies that it may leads to deadlock.

Comments

Process	Max Need	Allocated	Need	Remaining
P1	10	5	5	4
P2	9	3	6

Another process arrived and requested 3 resources but system assigned 2 and kept 2 as backup
 

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Process	Max Need	Allocated	Need	Remaining
P1	10	5	5	2
P2	9	3	6
P3	3	2	1

Now process P1 and P2 both requested 1 resources each before this point the system is in unsafe state but after this allocation system will be in deadlocked
 

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Process	Max Need	Allocated	Need	Remaining
P1	10	6	4	0
P2	9	4	5
P3	3	2	1

DEADLOCKED NO PROGRESS

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Thanks @saxena0612

What I conclude just check it.

Now according to the allocation in the third table, suppose P1 is again scheduled to the CPU and while executing if P1 request one more resource then P1 will be placed in Blocked state, then P2 will be scheduled and while executing, P2 also requested for resource then P2 will be placed in Blocked state and similar will happen with P3 also, now since in our system we have three process and all process are in blocked state, thus we can conclude that system in know in deadlock.

ryt ?

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Yes !! Any process that will request the same resource like here is this problem "TAPE DRIVE" will get blocked.