H13-821_V3.0 · Question #332
HDFS guarantees that a file can only be written by one caller at a time, but can be read by multiple callers at the same time.
The correct answer is A. True. HDFS enforces a single-writer model through a lease mechanism: when a client opens a file for writing, the NameNode grants it an exclusive lease, blocking any other client from writing to that file simultaneously. This design is intentional - HDFS was built for large-scale…
Question
HDFS guarantees that a file can only be written by one caller at a time, but can be read by multiple callers at the same time.
Options
- ATrue
- BFalse
How the community answered
(20 responses)- A75% (15)
- B25% (5)
Explanation
HDFS enforces a single-writer model through a lease mechanism: when a client opens a file for writing, the NameNode grants it an exclusive lease, blocking any other client from writing to that file simultaneously. This design is intentional - HDFS was built for large-scale batch workloads following a write-once, read-many pattern, so strong write exclusivity is baked into the architecture. Multiple clients can, however, hold concurrent read handles on the same file without conflict, since reads do not mutate data. Option B is wrong because HDFS does make this guarantee explicitly; it is not left undefined or implementation-dependent.
Memory tip: Think of HDFS as a library book policy - only one person can "check out" (write) a book at a time, but unlimited people can "read a copy" simultaneously.
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