Slow checksum calculation in VM Guest

[ChrisNRW]

Hello,
we have a PVE 7.3 running and one VM is a Windows 10 guest, that is used to make backups from some files.
A CMD script makes these steps:
- mapping a network drive to a share on a netwerk drive (NAS)
- copy multiple 1GB files from network to a USB drive (attached to the W10 guest)
- calculating checksums for the source files (MD5 by fsum.exe)
The copy process uses the complete 1Gbit/s LAN speed
Calculation of the checksum takes approximately twice the time, although CPU is really low (<20%) and LAN is ~300Mbit/s
Is there a bottleneck for calculating checksums?
iirc before the upgrade from PVE6 to 7 the checksum was as fast as the copy.
Thanks for reply.

 

[Matthias.]

Please show your VM config (output of qm config $VMID)
Is the checksum still slow when copying the data to a lokal drive and running the checksum calculation there?

 

[ChrisNRW]

Hello!

I made a test on a Windows 7 VM and it finishes in less than half of the time of the W10 VM.

Is it because of the differences in the VM config like LAN NIC (e1000 vs virtIO), Firewall or Chipset (i440fx vs q35)
or is there a low hash rate vlue in W10 like on Nvidias Graficcards?

Will try to make a test on lokal vHDD without LAN.

Win 10 VM:
agent: 1 boot: order=sata0;ide0 cores: 4 ide0: W116-NAS:iso/virtio-win-stable-0.1.229.iso,media=cdrom,size=522284K machine: pc-q35-6.0 memory: 8192 name: Win10 net0: virtio=AA:BB:CC:DD:EE:FF,bridge=vmbr0,firewall=1 numa: 0 ostype: win10 sata0: local-lvm:vm-105-disk-0,size=120G,ssd=1 scsihw: virtio-scsi-pci smbios1: uuid=240aeb4a-48c2-4644-9301-e7d8b619ec3 sockets: 1 vga: std

Win 7 VM:
agent: 1 boot: cd bootdisk: sata0 cores: 4 ide2: none,media=cdrom memory: 8192 name: Win7 net0: e1000=AA:BB:CC:DD:EE:FF,bridge=vmbr0 numa: 0 onboot: 1 ostype: win7 protection: 1 sata0: local-lvm:vm-100-disk-0,size=144G,ssd=1 sata1: local-lvm:vm-100-disk-1,size=100G scsihw: virtio-scsi-pci smbios1: uuid=29037bfb-2f1d-46a5-8702-25ad5df5e19 sockets: 1 usb0: host=2-4,usb3=1 vga: std

 

[Matthias.]

So first of all, you're not using cpu host, so everything is bound to be slow.
I doubt the chipset makes a bit difference, but best to try it out.
Same for network, best to try out both and benchmark.

 

[ChrisNRW]

Is it recommended to use cpu host?
The copy process reaches 1Gbit/s LAN speed with no Problem.
And the checksum process causes less than 20% cpu so i don't see the bottleneck.
I will do some more tests.

thx