VM Freezes, when large file is copied on Host PC

[Ralf Beißwänger]

Hello,

We have the problem, when we copy a big file in the background from our Networkshare to a local drive on the host PC (not to the VM) and parallel use a VM, the VM freezes and get unresponsive. For the copy time.

This only occurs, if the VMware Workstation isn't started with Admin rights.

When I start the Workstation with Admin Rights everything is fine.

Also this only occurs if the file is copied from a SMB Share, if I move this locally between drives, everything works fine.

We see this with Version 25H2 and 17.5.4

Has some else seen this problem?

-------------------------------------------

[RaSystemlord]

What is the Host and what is the HDD technology?

[Ralf Beißwänger]

It's on different Host PCs and Models with WIndows 11 25H2, i7, 64 GB Ram. The HDD is an M2 nvme with 4 TB.

-------------------------------------------

[richard612]

Very peculiar.  I've never heard of an I/O bottleneck that disappears with user elevation.

Is there an antivirus, data loss-prevention, or auditing agent running on the impacted hosts?  

I'm trying to envision how this could happen.  The only scenario that comes to mind is one of the above agents on a virtualization host either mis-configured or malfunctioning.

-------------------------------------------

[RaSystemlord]

Richard...

Yes, this is strange. On (real) HDD there are easily bottlenecks in I/O, but this is nVME. VMware itself should not be running on extra low priorities.

The question perhaps remains that what is the copying method? Windows or some extra application?

You can, perhaps, try to get rid of this, by using robocopy (in Windows command line). Perhaps familiar with that?

robocopy /e /v /Z e:\source_directory  c:\target_directory

Robocopy deals, by default, with directories and all the files in them. If not obvious, you can also "cd /d" to the target directory and then give the command from there giving " . " as the target - this slightly a bit more safe method.

(By default, it copies only not-already-copied files and you can run this many times, if networking or something else is failing in the meanwhile. There are MANY more options to this, but the above gives the basic copying just fine. The end result is always 100% if it ends well, and gives the summary to confirm.)

I mean, robocopy could run "with a lower priority" than anything else and thus your problem would be solved.

There can of course be a driver/device problem on the target or VMware VM device. Try using some other drive (USB 3.2 Gen 2 are fine, too). Windows OS itself shouldn't be a problem by default.

Well, there is one other candidate: Your VMware performance is near the edge, because a virus scanner is scanning VMware disk files - which it obviously shouldn't do.

[Ralf Beißwänger]

I test it with Robocopy, there is no freez, when I copy from the network share to local disc on host PC. So it's a thing between, no admin rights for the VM Workstation, SMB Share as copy Source and Windows Explorer.

The only problem is, robocopy is no Option for my Users, as they are not so familar with CMD commands and we want to get rid of the Admin permissons for the VMware Player.

Thank you

-------------------------------------------

[RaSystemlord]

Thanks, good to know!

There are two things left then:

1.
There are programs with GUI that have (to my knowledge), robocopy as the backbone. I have never used them and thus cannot give you any tips, but I think some of them would work for your Users.

2.
The reason why Admin user works and now the robocopy works - you seem to have corporate Users and Systems. As I mentioned before, I don't think Windows does this by default. NOW, you might have a group policy, quotas or something, that affects. Robocopy, since it only copies files one by one, does not hit those Group Policy limitations. This is just a theory - nothing more.

[Ralf Beißwänger]

Hello, 

In the past days I test a lot. Now I can say more about the problem. It's not directly the SMB Share the problem. The problem occurs if I add the SMB Share with a Drive letter to my Host PC and then copy something from my SMB Driveletter Z: to my local disc.

If I go direct to the unc path in the Explorer and copy to local, everything works fine, no freeze.

That's why the problem didn't occure when I run the Workstation as admin, because then the Driveletter isn't available.

But I don't have a clue, why the drive letter for the SMB Share change here something for the VM Workstation.

-------------------------------------------

[RaSystemlord]

Ralf,
to my understanding, you said/suggested before that there was no problem when using robocopy, even with a drive letter, even with the standard user.

If that is true, you have something very wrong in your Windows. Is it a language version and not English? Or perhaps you have your own version of Windows that is cloned to everybody? You could try this out by creating a Microsoft Windows from their ISO file and try with that - I understand you might not be able to connect to your Domain with that, but you could have that in VMware, under NAT (which does have access to everything that the Host has).

In the past, I have seen something like this happening (in principle, like this, not exactly this) when an "utility program" changed a system .dll, to something that didn't work. In principle, this shouldn't be possible since Win 10 or even before that, but well, there are many things in Windows that shouldn't happen but they still do.

[Ralf Beißwänger]

Hello Richard,

there is MS Defender on the Client machine. But I don't think this is because of the host PCs I/Os. I test it with a USB drive and copy on the host PC something to the local disk. Everything works fine. When I do the same thing from the SMB Network share and copy a large file to the local host disc, the opened VM freezes.

SMB Share copy:

USB disc copy:

-------------------------------------------

[kasper]

Never seen the problem.   May be a memory issue.   I would run 'process explorer' or 'task manager' and see if memory use keeps climbing til the freeze.  I would also consider set both the virtual and physical NIC to a fixed vs auto connect speed in device manager.

-------------------------------------------

[Rafael Fernando Stock]

Hello!

I was having the same issue where VMware would freeze when copying files from a local network server to the host; I searched on Google, and the AI ​​recommended this solution, which worked:

1. Disable Advanced Network Features on the Host (Windows 11)

Windows 11 has network offloading features that conflict with VMware virtual switches during large-scale transfers.

- In the Host's Start menu, search for "Network Connections."
- Right-click your physical network adapter (Ethernet or Wi-Fi) and select "Properties."
- Click the "Configure" button and go to the "Advanced" tab.
- Find and disable the following options:
     - IPv4 Checksum Offload; 
     - Large Send Offload v2 (IPv4); 
     - Receive Side Scaling (RSS);
     - Click OK. This forces Windows 11 to process network packets linearly, preventing the buffer overflow that causes the disk to freeze.

I couldn't find the "Receive Side Scaling (RSS)" option, but it worked anyway. According to the AI, it is perfectly normal not to find "Receive Side Scaling (RSS)" on some network adapters, especially with Wi-Fi connections or motherboards using generic Windows drivers. You can skip that specific option, as disabling "Large Send Offload" (LSO) and "Checksum Offload" already resolves the main communication bottleneck with VMware.

I hope this helps.