We recently read that on proxmox, which is where we have about 10 FreePBX distro VMs, the default processor type “kvm64” is essentially equivalent to a Pentium 4 in it’s CPU flag set.
We changed all our VMs to the “host” processor type, as we aren’t doing live migrations. We saw a huge drop in CPU load on all processes within the VMs after we did this.
Probably four hours later, all these FRACKs started, but just on one of the 10 VMs.
As I mentioned near or at the top of this post, we have only had this issue on servers that use TCP for SIP, and a non standard port (not 5060). Our UDP servers have never had the issue. That said, from the several months of research and feedback from experts, that shouldn’t matter. We strongly prefer TCP and the non standard port for security and NAT traversal.
EDIT: Also, eight or so others of the VMs are setup the same way as the one that crashed, and on the same proxmox host.
CORRECTION: the FRACKs started a little over a day after the processor type change. However, non of the other VMs are having this issue.