One strategy to keep file writes atomic is to ??,
configure appropriate system settings such as KEEP_FILE_WRITES_ATOMIC
write to a temporary file, then rename the temporary file to the original file name via system calls
use a write-through cache to store the file until it can be written atomically
write the file once, read it back, and then rewrite it
concatenate the new file to the existing file
The Correct Answer and Explanation is :
The correct strategy to keep file writes atomic is to write to a temporary file, then rename the temporary file to the original file name via system calls.
Explanation:
Atomic operations are indivisible and uninterruptible, ensuring that a file write operation is completed entirely or not at all. This is crucial for maintaining data integrity, especially in scenarios where system crashes or power failures might occur during a write operation.
Writing to a temporary file and then renaming it to the original file name is a widely adopted method to achieve atomic file writes. This approach leverages the atomicity of the rename system call, which is guaranteed by many operating systems, including POSIX-compliant systems. The steps involved are:
- Create a Temporary File: Write the new data to a temporary file.
- Rename the Temporary File: Use the
renamesystem call to replace the original file with the temporary file.
The atomicity of the rename operation ensures that the original file is replaced entirely by the new file, or not at all, even in the event of a system crash. This method is effective because the rename operation is typically atomic on many file systems, meaning it either completes successfully or has no effect, leaving the original file unchanged.
It’s important to note that this approach assumes the temporary file and the original file reside on the same file system. If they are on different file systems, the rename operation may not be atomic, and additional steps, such as copying the file and then deleting the original, would be necessary.
Other strategies, such as configuring system settings like KEEP_FILE_WRITES_ATOMIC, using write-through caches, or writing and rewriting the file, do not inherently guarantee atomicity and may not be reliable for ensuring data integrity.
In summary, writing to a temporary file and then renaming it to the original file name via system calls is a robust and widely used method to achieve atomic file writes, ensuring data integrity even in the face of unexpected system interruptions.