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GCFA · Question #181
GCFA Question #181: Real Exam Question with Answer & Explanation
The correct answer is B. sync. The Unix 'sync' command flushes all pending writes from the kernel buffer cache to disk, ensuring data integrity before system shutdown or disk operations.
Question
You work as the Network Administrator for McNeil Inc. The company has a Unix-based network. You want to run a command that forces all the unwritten blocks in the buffer cache to be written to the disk. Which of the following Unix commands can you use to accomplish the task?
Options
- Atune2fs
- Bsync
- Cswapoff
- Dswapon
Explanation
The Unix 'sync' command flushes all pending writes from the kernel buffer cache to disk, ensuring data integrity before system shutdown or disk operations.
Common mistakes.
- A. tune2fs is used to adjust tunable filesystem parameters on ext2/ext3/ext4 filesystems, not to flush buffer cache to disk.
- C. swapoff disables the use of a specific file or partition as swap space, which is unrelated to flushing buffer cache writes.
- D. swapon enables a file or partition for use as swap space, which has no function in flushing unwritten buffer cache blocks to disk.
Concept tested. Unix sync command and buffer cache flushing
Reference. https://man7.org/linux/man-pages/man8/sync.8.html
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