PrepBharat

1. All processes share a semaphore variable mutex, initialized to 1. Each process must execute wait(mutex) before entering the critical section and signal(mutex) afterward.
Suppose a process executes in the following manner.
wait(mutex);
.....
critical section
.....
wait(mutex);
a) a deadlock will occur
b) processes will starve to enter critical section
c) several processes maybe executing in their critical section
d) all of the mentioned

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2. A collection of instructions that performs a single logical function is called ____________
a) transaction
b) operation
c) function
d) all of the mentioned

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3. A terminated transaction that has completed its execution successfully is ____________ otherwise it is __________
a) committed, destroyed
b) aborted, destroyed
c) committed, aborted
d) none of the mentioned

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4. The state of the data accessed by an aborted transaction must be restored to what it was just before the transaction started executing. This restoration is known as ________ of transaction.
a) safety
b) protection
c) roll – back
d) revert – back

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5. Write ahead logging is a way ____________
a) to ensure atomicity
b) to keep data consistent
c) that records data on stable storage
d) all of the mentioned

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6. In the write ahead logging a _____________ is maintained.
a) a memory
b) a system
c) a disk
d) a log record

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7. An actual update is not allowed to a data item ____________
a) before the corresponding log record is written out to stable storage
b) after the corresponding log record is written out to stable storage
c) until the whole log record has been checked for inconsistencies
d) all of the mentioned

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8. The undo and redo operations must be _________ to guarantee correct behaviour, even if a failure occurs during recovery process.
a) idempotent
b) easy
c) protected
d) all of the mentioned

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9. The system periodically performs checkpoints that consists of the following operation(s) ____________
a) Putting all the log records currently in main memory onto stable storage
b) putting all modified data residing in main memory onto stable storage
c) putting a log record onto stable storage
d) all of the mentioned

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10. Consider a transaction T1 that committed prior to checkpoint. The <T1 commits> record appears in the log before the <checkpoint> record. Any modifications made by T1 must have been written to the stable storage either with the checkpoint or prior to it. Thus at recovery time ____________
a) There is a need to perform an undo operation on T1
b) There is a need to perform a redo operation on T1
c) There is no need to perform an undo and redo operation on T1
d) all of the mentioned

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