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Exam 1z0-068 topic 1 question 27 discussion

Actual exam question from Oracle's 1z0-068
Question #: 27
Topic #: 1
[All 1z0-068 Questions]

Which two statements are true about the Global Enqueue Service, Instance Locks, and global enqueues in Oracle 12c RAC?

  • A. In a RAC One Node database, there is no LMD0 process if only one instance is running.
  • B. Global Enqueues and Instance Locks replace mutexes completely in RAC database instances.
  • C. In a RAC database, there is no LMD0 process if only one instance is running.
  • D. Global Enqueues and Instance Locks replace latches completely in RAC database instances.
  • E. Global Enqueues may have owners and waiters in the same instance.
  • F. Global Enqueues may have converters and waiters in the same instance.
Show Suggested Answer Hide Answer
Suggested Answer: AF 🗳️
F: A convert queue is a queue of locks that are waiting to be converted to particular mode, this is the process of changing a lock from one mode to another, even a
NULL is a lock. A resource has a lock value block (LVB). The Global Resource Manager (GRM) keeps the lock information valid and correct across the cluster.
Oracle 10g release 2 and beyond replaced some latch mechanisms with the mutex approach, claiming that they are faster and more efficient than traditional locking mechanisms.
Incorrect Answers:
B, D: Mutexes are objects that exist within the operating system to provide access to shared memory structures. They are similar to latches.
References:
http://www.datadisk.co.uk/html_docs/rac/grd.htm
by hereisash at Feb. 27, 2021, 7:43 a.m.

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JVarelaC
3 days, 20 hours ago
what happens when in a One Node RAC database is needed to start a new instance for maintaining purposes? I think exists always a lmd0 process in RAC databases be One node or not; so my answer is E,F
upvoted 1 times
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Yoones
2 years, 1 month ago
AF is correct.
upvoted 2 times
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hereisash
2 years, 9 months ago
BF, why no LMD process in one node RAC? Its a RAC DB afterall
upvoted 1 times
bestsalman
1 year, 3 months ago
no , LMD0 will lock for global lock , which is remote lock , that is mean there is another instance will access , in one node RAC there is only on instance .
upvoted 1 times
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