N-central Troubleshooting

My N-able N-central Server Won't Boot; citing a Kernel Panic

Last Modified

Mon Mar 13 12:37 GMT 2023

Description

You're booting your server for whatever reason (maintenance, power outage, etc...), and the server will not boot, claiming a Kernel Panic during boot.

Environment

N-able N-central (any version)

Solution

Check the system meets the Specification as per the Install Guide.
Perform hardware diagnostics, especially of RAM and Disk.
If virtualized, such as in VMWare or Hyper-v,
1. Check that vhd optimization, vMotion, and/or live snapshotting is disabled
2. Ensure memory/cpu is dedicated, not just allocated (minimum RAM = maximum RAM and not overallocated on the host)
3. Consider suspending other VMs or guests and observe the results.
4. Created a new Guest or VM from scratch, install N-able N-central and perform a restore.
If the server is still not rebooting, and you have no Snapshot or N-able N-central backup, you can attempt to recover the ncentral-mycompany-2020xxxxxxxx-daily.tar and .sha1 file using Linux Rescue, or using the vm file (if applicable). Then, a Rebuild and Restore can be attempted.
1. See your virtualization vendor's documentation, or instructions for Linux rescue. Some example links below.
  - Linux Rescue: https://docs.centos.org/en-US/centos/install-guide/Rescue_Mode/
  - VMWare files extraction: https://www.vmwareblog.org/4-ways-extract-content-vmdk-vm-totally-dead/
  - Hyper-v and others: https://www.raymond.cc/blog/access-virtual-hard-disks-easily-in-windows-7/
If you are still having an issue, please reach out to Support via phone or through an emergency case and a representative will reach out to you as soon as possible.

Detail

A Kernel Panic indicates a deep-level issue which cannot be resolved by support, often due to a hardware issue or severe crash of your N-able N-central server. In the case of a Kernel Panic, you'll need to perform a rebuild of your N-able N-central server and restore your database from a recent backup. KB article 000042228 will walk you through the process of restoring your N-able N-central server.

Note: We have also observed kernel panic errors from dynamic volumes and volumes that are configured for 'vhd optimization'; it is best practice to use dedicated RAM, CPU. The virtual drive must also be thick provisioned as a fixed or non-dynamic volume for maximum stability.