Problem Windows Server 2022 + RDS + FSlogix

[sverchok16]

Hi,
I have a VM running Windows Server 2022 with RDS farm + FSLogix.
Environment:

• Proxmox VE 9
• Kernel: Linux 6.17.4-2-pve (2025-12-19T07:49Z)
• Host CPU: AMD EPYC 7443P (24 cores, 1 socket)
• VM CPU: 24 vCPUs (host type)
• VirtIO drivers version: 0.1.285

Issue:
At random moments the VM CPU usage jumps to 100%.
The “System” process consumes most of the CPU.
Process Explorer shows heavy usage in:

• vhdmp.sys
• ntoskrnl.exe

At the same time, disk I/O inside Windows (Resource Monitor) goes to 100%.
This server is used as an RDS farm with FSLogix profile containers.
Has anyone experienced similar behavior?
Could this be related to:

• VirtIO drivers?
• Disk configuration?
• High vCPU count?
• FSLogix profile containers?
• Possible misconfiguration of the virtual machine (NUMA settings, machine type, CPU type, ballooning, IO thread settings, storage backend tuning)?

Any suggestions would be appreciated.
CONFIG:
agent: 1,freeze-fs-on-backup=0
allow-ksm: 0
balloon: 0
bios: ovmf
boot: order=scsi1
cores: 22
cpu: host
efidisk0: pvs4-pool-vm:vm-114-disk-1,efitype=4m,ms-cert=2023,pre-enrolled-keys=1,size=1M
machine: pc-q35-10.1
memory: 163840
meta: creation-qemu=10.1.2,ctime=1765794630
name: WINRDS02
net0: virtio=BC:24:11:82:1E:37,bridge=vmbr1,mtu=1500
numa: 0
onboot: 1
ostype: win11
sata0: none,media=cdrom
scsi1: pvs4-pool-vm:vm-114-disk-0,iothread=1,size=700G
scsihw: virtio-scsi-single
smbios1: uuid=f8c7fa8e-e994-4d49-a2c7-9ae5208acf65
sockets: 1
vmgenid: 825a8524-20a3-489b-b62f-db5f0b9a0a9b

 

[ness1602]

For my customers we are using rds farm + fslogic on CEPH tbh, not on local disks. Try changing cpu type to something instead of host. Also maybe screenshots of load and io of the VM,maybe you have something like I/O stall?

 

[sverchok16]

FSLogix profile containers are stored on a high-performance SAN storage and accessed over the network via SMB. We have also tested different CPU types (including non-host types), but the issue persists. We have disabled the VM’s screenshot functionality to rule out any potential impact on performance.
Our RDS farm consists of multiple VMs with identical configurations.
The high CPU / disk activity issue occurs randomly on only a single VM.
If the SAN storage were the cause, we would expect all VMs to experience the same behavior concurrently.