Problem Windows Server 2022 + RDS + FSlogix

S

sverchok16

New Member
Oct 14, 2025
3
0
1
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
 
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?
 
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.
 
sverchok16 said:
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.
Click to expand...
Hi sverchok16,

Have you been able to get in to bottom of this issue and resolve it finally?
We do have exactly same issue on our RDS Session Hosts suddenly. We do have entire RDS SH fleet running on Proxmox + File Server (Windows with DFS) and our 12 session host randomly reach out to 100% CPU (one at a time) causing the system to collapse.
Low level anlaysis proved that the cause for the 100% CPU is coming from SYSTEM dealing with vhdmp.sys.

Problem started out in September, most likely after patching.
 
Hi,Arek K.

Not fully resolved yet, unfortunately, but I can share what we’ve found so far. It may save you some time.


In our case the problem is not caused by the September updates: we were seeing the same hangs before them. The September CU did have a confirmed RDS issue (Remote Desktop Services could stop responding), but Microsoft fixed it with the out-of-band update KB5129237 on 14 Sep, and the fix is included in all later updates, including the October CU. See the Microsoft release health page: https://learn.microsoft.com/en-us/windows/release-health/resolved-issues-windows-server-2022


Also, the symptoms of that issue look different from ours: there, RDS hangs on user logoff, reportedly due to a deadlock between Remote Desktop and the Local Session Manager, not vhdmp disk resets.


What the failure looks like on our side:


  1. Event 11 in Microsoft-Windows-VHDMP-Operational: a Flush fails with 0xC000009A (STATUS_INSUFFICIENT_RESOURCES).
  2. Then disk event 51 and repeated vhdmp event 129 (reset to device \Device\RaidPort3, which is the virtual adapter shared by all mounted FSLogix containers).
  3. Effectively the VM loses the container disk, but FSLogix still treats it as attached. The resets keep piling up until the whole server hangs.

It happens at random. A server can run fine for a month, or hang after just two days, and we haven’t found any pattern across our servers.


What we ruled out: SAN/multipath on the Proxmox node, load on the file server, Kerberos, MTU, the SMB client, and antivirus (it was disabled during both incidents).


We also updated the VirtIO drivers to 0.1.302 and FSLogix to 26.08 (3.26.826.17182). That didn’t help.
 
You must log in or register to reply here.
Top Bottom
Back