Week 4 Flashcards
In GFS, does file creation require a lock on the directory structure?
no
what does a read lock do
prevents a dir from being deleted, renamed or snapshotted
what does a write lock do
what do you do when:
What do you do when:
after a file is deleted, does GFS reclaim the space immedietly
no, does it lazily during garbage collection
What exactly happens when a file is deleted in GFS
What is the role of heart beats in garbage collection
what causes a stale chunk replica
what does working with stale replicas cause
What 3 things happen when a master grants a new lease on chunk
Is the GFS optimized for large number of small files
no
what are the primary nature of operations on files in GFS
in mapred, what happends when the config property is set to local
whole job will be done in a single jvm
what does the submit() call do on a job object
creates an instance of a JobSubmitter
What does the tasktracker do
what does a taskrunner do?
how is time split up between tasks in the reducer?
what does the % in the mapper mean
Who sends heartbeats to the jobtracker every 5 seconds
tasktracker
what does the jobtracker do
What is the main purpose of YARN
what is the resource manager in YARN
what is the node manager in YARN
what is the application master in YARN
What is a small job?
What happens when a child task fails in classic MR
what is the type of failure which hadoop has no mechanism for dealing with
jobtracker failure
