KVM and NFS Storage

[noesberger]

Hi

I have installed CentOS Linux release 7.3.1611 (Core), Kernel 3.10.0-514.26.2.el7.x86_64.
I have installed qemu-kvm and since my last upgrade, I have problems that some VMs are freezing. In the messages.log I can see:
Jul 19 04:05:41 nuc01 kernel: nfs: server 192.168.1.200 not responding, still trying
Jul 19 09:19:51 nuc01 kernel: nfs: server 192.168.1.200 OK
Jul 19 09:22:51 nuc01 kernel: nfs: server 192.168.1.200 not responding, still trying
Jul 19 17:00:56 nuc01 kernel: nfs: server 192.168.1.200 OK
Jul 20 08:30:12 nuc01 kernel: nfs: server 192.168.1.200 not responding, still trying
Jul 20 17:44:08 nuc01 kernel: nfs: server 192.168.1.200 OK
Jul 20 19:29:16 nuc01 kernel: nfs: server 192.168.1.200 not responding, still trying

But the nfs Server (Synology) is responding and other VMs on the same storage are running fine.
When I searched in the web for the error, some users were able to fix it with: sysctl vm.dirty_ratio=10. But for me it didn't helped.

Has someone the same issue or can help me with the problem?

Thanks for any help.