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Imac Copy Network Files Continue on Error

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Frustrated man in front of a computer

UPDATE: This issue was fixed in macOS 10.15.5

Hearing From Our Customers

Are you working on a movie set, transferring hundreds of gigabytes from a camera card to a RAID array? Are you a photographer trying to copy a large project from one volume to another?

If so, you may have already encountered hangs copying files after you upgraded to macOS 10.15.4. When you encounter the hang we are discussing, you can still move your mouse but are no longer able to copy files.

Investigating the Hang

A few days after the macOS 10.15 update was released, we began to hear of "Finder hangs" from DITs (Digital Imaging Technician) on movie sets. They were having their Macs stall when transferring hundreds of gigabytes of video from their 4K and 8K camera cards to their OWC ThunderBlades and ThunderBays. Anytime we hear about this type of problem, we immediately start looking for a cause.

A day later, we were able to reproduce the problem 100% of the time by copying 300 GB of large (10 GB) files from one SoftRAID RAID volume to another. Using a kernel debugger, we determined that the hang was not caused by an error in the SoftRAID driver. We then were able to reproduce the hang on an AppleRAID volume, using the AJA System Test Lite test application.

Once we proved the hang was not a problem with the SoftRAID driver, we alerted Apple engineers to the issue and collected further information to help them with their investigation. I can't say when Apple will release the fix for this problem, but in the past, when they have been alerted to a hang or kernel panic, they had it resolved in the next update to macOS.

We will update this blog post once we have confirmed that this hang has been fixed in a future release of macOS.

We Discovered a Temporary Work-Around for macOS 10.15.4

If you want to prevent this hang, there is a setting in the computer's NVRAM, which can be changed as a temporary fix. NVRAM settings are saved in a dedicated chip in your Mac and determines settings such as the audio volume your Mac starts from, the output volume for sound, and which, if any, debugging features are enabled. One of these debug features allows you to disable the part of macOS which is causing the hang. This could result in a 5 – 10% slower read and write performance but will prevent the hang from occurring.

Note: To enable this setting, you will have to disable SIP (System Integrity Protection). SIP is a feature of macOS which offers advanced protection from malware. By disabling SIP, you could be making your Mac more susceptible to malware infections.

The instructions at the bottom of this post show you how to revert NVRAM to the original (default) settings and how to re-enable SIP. I recommend that after you disable SIP and change the setting in NVRAM, you attach a sticky note to your monitor, reminding you to revert these changes once Apple fixes this problem.

Instructions for Preventing the Hang in macOS 10.15.4

Changing the NVRAM setting requires that you disable SIP.

Steps to Change NVRAM so That Hangs Are Prevented

Disable SIP:

  1. Restart the computer and then press the Command + R keys simultaneously, once you hear the startup chime. Keep holding the keys down until the Apple logo appears (this may take up to 90 seconds).
  2. When the menu bar says: "macOS Utilities," you are booted into Recovery mode. Launch the Terminal application by selecting it from the Utilities menu.
  3. In the Terminal, type the following command:
    csrutil disable
  4. Afterward, the Terminal should display this message:
    Successfully disabled System Integrity Protection. Please restart...
  5. Select "Restart" from the Apple menu to restart your Mac.

Change the NVRAM Setting:

  1. In the Finder, select Utilities under the Go menu and then launch the Terminal application.
  2. In the Terminal window, type the following command:
    sudo nvram boot-args="dart=0"
  3. Restart your Mac normally, without any keys being pressed.
  4. To confirm that your NVRAM settings have been changed, relaunch the Terminal application and type the following command:
    nvram boot-args
  5. Check that the output from the command reads:
    boot-args dart=0

Instructions for Reverting Your Mac to a Normal Configuration

Once Apple releases an update to macOS 10.15, which fixes this issue, you can revert your Mac to the normal NVRAM settings and re-enable SIP.

Reset NVRAM to the default settings:

  1. In the Finder, select Utilities under the Go menu and then launch the Terminal application.
  2. In the Terminal window, type the following command:
    sudo nvram boot-args=
  3. Restart your Mac normally, without any keys being pressed.
  4. To confirm that your NVRAM settings have been changed, relaunch the Terminal application and type the following command:
    nvram boot-args
  5. Check that the output from the command reads:
    boot-args

Re-enable SIP:

  1. Restart the computer and then press the Command + R keys simultaneously, once you hear the startup chime. Keep holding the keys down until the Apple logo appears (this may take up to 90 seconds).
  2. When the menu bar says: "macOS Utilities," you are booted into Recovery mode. Launch the Terminal application by selecting it from the Utilities menu.
  3. In the Terminal, type the following command:
    csrutil enable
  4. Afterward, the Terminal should display this message:
    Successfully enabled System Integrity Protection. Please restart...
  5. Select "Restart" from the Apple menu to restart your Mac.

UPDATES

Hang fixed in macOS 10.15.5

We have just finished testing with macOS 10.15.5 and have confirmed that this hang no longer occurs.

Hang also observed when copying to a server

Larry Jordan, the renowned creator of education material on video editing and post-production, contacted us after he encountered the same problem transferring a large amount of data from his iMac to a Synology server. He wrote about it in his latest weekly newsletter.

The NVRAM fix disables WiFi on some Macs

We have heard from numerous customers that the above change to NVRAM makes their WiFi networking no longer work. Users have reported this with MacBook Pros which contain T2 chips but it may affect addition Mac models.

If you encounter this problem, you can follow the steps above in the section "Instructions for Reverting Your Mac to a Normal Configuration." You can then disable the Write Cache in the SoftRAID driver. This will prevent the hang from occurring but the write performance of your volume will be significantly decreased.

To disable the write cache in the SoftRAID driver:

  1. Launch the SoftRAID application.
  2. Select Preferences from the SoftRAID menu
  3. Select the RAID tab at the top of the Preferences window
  4. Unselect the checkbox next to "Enable write cache" so no checkmark appears in the box.
  5. Click the Save button at the bottom right of the Preferences window.

Tim Standing

the authorOWC Tim

Vice President of Software Engineering, Mac

Tim Standing has been writing drivers and storage utilities for Mac OS since 1986. He is the creator of SoftRAID for macOS and is currently VP of Software Development - Mac at Other World Computing, Inc. He has patented a write acceleration technique that enables the write speed RAID volumes to be as fast as the read speed. Tim's team is responsible for SoftRAID, OWC Dock Ejector, OWC Drive Guide, and all Mac drivers and utilities that make OWC products exceptional. When he's not writing code, he's creating delicious pizzas in his wood-burning pizza oven.

harveyalifeen.blogspot.com

Source: https://eshop.macsales.com/blog/60773-why-is-my-mac-hanging-when-copying-files-after-upgrading-to-macos-catalina-10-15-4/

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