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As usual the main internal drive on which macOS gets installed is journaled. I was going through some Ask Different posts in which there was something mentioned as Disk journaling which saves you from file corruptions but each time it registers the status of your file at the present time.These registrations might be having a huge impact on your CPU and Disk (My Assusmption), so is there any way by which I can check if my disk has journaling turned on or not and if it has how to turn it off via terminal?

When I click on File Menu option via the menu bar after selecting my main Disk, this is what I get - Journaling is greyed out (I guess this option lights up if and only you are in recovery mode)

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You do not specify which version of macOS you are using. I will assume the current version (macOS 10.13.3).

Open the Disk Utility application and select the volume you wish to check. In the image below, "MyFish" has been selected.

Note: For a better view of an image, either click on the image or open the image in a new window.

Next, click on "File" in the menu bar. In the pulldown, you will see "Enable Journaling". If "Enable Journaling" is grayed out, then journaling is enabled, otherwise journaling is disabled. Below, the image shows the volume to have journaling enabled.

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The older versions of macOS, would allow for journaling to be disabled directly from the Disk Utility application. With macOS 10.13.3, journaling can be disable by using the diskutil command. Below is the command to disable journaling for the "MyFish" volume.

diskutil  disableJournal  MyFish

Similarly, journaling can be enabled by using the command below. As stated earlier, this can also be accomplished from the Disk Utility application.

diskutil  enableJournal  MyFish
  • After I disable disk journaling I would have manually save each file right cause before I used to quit edited images nad files without saving them and when I used to open them back they were as it was left, from now that won't happen I guess? – Sayan Feb 13 '18 at 4:49
  • The macOS operating system uses virtual memory. This allows the operating system to use space on a drive to emulate RAM. Traditional applications open a file and copy the contents to RAM. Sometimes this RAM is actually space on a drive. What you are suggesting is the opposite. Instead of copying the file to RAM, the RAM gets mapped to the existing file. So while the application has the file open, some part of the stored file may exist on the drive or in RAM. – David Anderson Feb 13 '18 at 6:09
  • What is important is that if there is a crash, the operating system must always write the RAM back to where it is mapped on the drive. So there is no need to save a file. This the basis of how a Real Time computer works. Both Apple and Microsoft are integrating this abilty into their operating systems. Most applications still access files the traditional way, but these Real Time methods have appeared in a few simple editors. – David Anderson Feb 13 '18 at 6:09
  • So what consequences I will face after disabling journaling? – Sayan Feb 13 '18 at 6:54
  • NTFS (Windows), ext4 (Linux), JHFS+ and APFS (Apple) all have some form of journaling. The idea is to record your transaction before you do it. If the transition fails, then all effects of the failed transaction can be erased. This is done in an effort to prevent a drive from being corrupted. If you turn journalling off, then the file system is no safer than MS-DOS FAT or ExFAT file systems. So NTFS, ext4, JHFS+ and APFS have a much better chance of recovering from a program crash, power failure or other hardware/software mishap. – David Anderson Feb 13 '18 at 8:04

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