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COP4610 Final with verified answers
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COP4610 Final with verified answers
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COP4610 FinalWhich disk allocation policy is least reliable? - correct answer ✔✔linked-list allocation
Which disk allocation policies offer efficient random accesses? - correct answer ✔✔continuous
allocation, index-based allocation, multi-level indexing
Most files are... - correct answer ✔✔small
Which namespace is most prone to name collisions? - correct answer ✔✔flat name space
free blocks, directories, file headers, indirect blocks are an example of... - correct answer ✔✔metadata
ad hoc file system check - correct answer ✔✔fsck
all operations either happen or they do not - correct answer ✔✔atomicity
transactions appear to happen one after another - correct answer ✔✔serializability
once a transaction happens, it is recoverable and can survive crashes - correct answer ✔✔durability
Write a program create_files in any language to create a file foo, sleep for 5 seconds, and create a file
bar.
Right after you start the program, press Ctrl-C to prevent the program from completing. What do you see
in the directory? - correct answer ✔✔foo
Write programs atomically_create_files and
replay_journal so that files foo and bar are atomically created. First, atomically_create_files logs <begin
, transaction> into the journal file journal. Second, atomically_create_files logs <create foo> and <create
bar> into journal. Third, atomically_create_files logs <commit> into journal. A second replay_journal
program can read the journal file to perform the actual file creations and delete journal. If there is a
crash before <commit> is written into journal, replay_journal just deletes journal. If there is a crash
before replay_journal can complete the creation of
the two files, replay_journal can be run again to recreate both files. Finally, after both files are created,
replay_journal removes journal.
You can inject crashes by exiting at various points in various programs. First, copy the program
atomically_create_files to atomically_create_files_crash. Insert a cra - correct answer ✔✔nothing
Write programs atomically_create_files and
replay_journal so that files foo and bar are atomically created. First, atomically_create_files logs <begin
transaction> into the journal file journal. Second, atomically_create_files logs <create foo> and <create
bar> into journal. Third, atomically_create_files logs <commit> into journal. A second replay_journal
program can read the journal file to perform the actual file creations and delete journal. If there is a
crash before <commit> is written into journal, replay_journal just deletes journal. If there is a crash
before replay_journal can complete the creation of
the two files, replay_journal can be run again to recreate both files. Finally, after both files are created,
replay_journal removes journal.
You can inject crashes by exiting at various points in various programs. First, copy the program
atomically_create_files to atomically_create_files_crash. Insert a cra - correct answer ✔✔foo and bar
Security is a form of... - correct answer ✔✔policy
Which of the keys are used to encrypt (not decrypt) a message when anyone can create the message,
but only A can read the message? - correct answer ✔✔public key of A
secret data remains secret - correct answer ✔✔confidentiality
unauthorized user should not be able to modify data - correct answer ✔✔integrity
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