Exchange 2016 Troubleshooting: DAG Seeding Failure

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As many of you know, DAG seeding can fail for a few reasons, namely:

  • Networking issues
  • Resource issues (CPU/RAM)
  • Disk space issues
  • Anti-virus (exclusions missing)
  • And many more.....

Today we had a strange one though, some databases seeded fine but the rest were failing with this error:

https://www.collaborationpro.com/wp-content/uploads/2020/07/image-2.png

Here are some of the troubleshooting steps to try and save you time:

  • Remove Antivirus even though exclusions are in place.
  • Reboot Server to ensure no pending reboots from patching etc.
  • Mount points have enough space.
  • Memory and CPU enough to handle the load.

Even though all the above was done, the seeding would start and then fail about 5 minutes in.

The solution was to move the Virtual Machine to another host and after that the seeding went through without an issue. Potential problems at play here:

  • Host Network driver issue
  • Host lockup
  • Network cable faulty on the Physical server

It could have been anyone and the server will be investigated but check your hosts first by doing a VM migration and then see if the seeding goes through.