In an event of a power failure or any other disaster which prevents this update to the file system directories, the operating system will take an unexpected amount of time to start again since the system will have to perform a consistency check that requires it to go through the entire file system block by block. However, this process results in write overheads it is worth it. This way a record is maintained of the current transactions, that happen. Additionally, it also marks the action as completed in the journal once the task has been executed. Before the operating system commits to any action, it makes an entry in the “Journal” and then executes the transaction. With every write and read operations, file system directories are updated with the file locations and other data. Manually activating and deactivating the journaling feature is discussed later in this blog.
If the drive is formatted in Mac OS X Extended (Journaled), then by default, journaling is active on the drive. Additionally, restarting the system gets faster due to journaling. However, the data that was in the buffer while the system failed, may be lost but the system is reinstated to the working state. In an event of an abrupt shutdown of the system due to power outage or another failure, these journal entries make it possible to restore the system to the last known consistent state of working. All of this happens automatically on OS X. These entries are maintained in a special type of data structure called “ Journal”. When the journaling is enabled on Mac, it keeps record entries of the changes to the files present on the disk. Journaling is a Mac OS X feature that is extremely helpful in protecting the system against the problems that arises due to power failures, hardware failures and directory corruptions. Topics covered in the blog are as follows:
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If for any reason Disk Utility fails to wipe your drive. Wipe External Hard Drive on Mac via Terminal (Command Line) It’s because SSDs don’t have to go through this process due to the way it manages files. Note: If your drive is an SSD, you won’t be able to click “Security Options” as this option will be grayed out. Here you can specify how securely you want to wipe the drive, move to Most Secure if you are paranoid because this option overwrites more times to the disk space, though the process tends to be slower.Next, click the Security Options button at the bottom.Choose a file system to which you want to format your external drive.Select the disk or volume in the list on the left panel.