Home > Virtualization > Awful FreeBSD Write Performance Under VMWare Server 2.0

Awful FreeBSD Write Performance Under VMWare Server 2.0

I can’t say for sure if this is just in VMWare Server 2.0, but the write performance of FreeBSD under VMWare has been AWFUL.  I currently use FreeNAS as my NAS and media server at home; I’ve always found it full featured but a little slow under VMWare.  I’ve done all the recommended tuning changes:

  1. Don’t use the lnc network driver, but the Intel e1000, put ethernet0.virtualDev=”e1000″ in the virtual hosts VMX file
  2. Reduce  kern.hz in loader.conf:  kern.hz=100
  3. Use SCSI Virtual Disks

My home network is GigE using an 8 port Linksys SRW208P, the virtual machine host running VMWare server 2.0 is Linux Ubuntu Server running on an Intel Quad core with 4GB RAM and two (2) Software mirrored LVMed hard drives.

My very non-scientific benchmark, copying a 660MB file using SMB between Linux and FreeBSD

Read = Copying from VM to Windows Machine

Write = Copying to VM from Windows Machine

  • FreeBSD 6.4-RC2 (FreeNAS) Guest: Read: 43s Write: 87s
  • FreeBSD 7.0-Release: Read Guest: 37s Write: 147s
  • Ubuntu Linux 2.6.24-19-virtual Guest: Read: 36s Write: 29s
  • Ubuntu Linux 2.6.27-7-server Host: Read: 29s Write: 31s
As you can see above the write performance to the FreeBSD VMs is AWFUL.  I did some previous testing with FTP and other protocols as a means to eliminate Samba on BSD as the source of the performance issues, this didn’t make any significant difference.  I must admitt that one would expect to see a gagabit network performing better than this; I chalk this up to an old Intel P4 Windows XP machine, pretty junky cabling that all is “pre-GigE” CAT5.  For example, I know that my laptop which is a newer DELL unit is 20% faster than the above “benchmark” times when connected directly to the Linksys switch.

So the question is, why does FreeBSD suck so bad under VMWare?  I can’t say for sure.  There is no doubt that Linux benefits from having VMWare tools vmnet interfaces, those drivers aren’t available for FreeBSD; yet it has to be more than that.  Unfortunately I don’t have an extra PC kicking around to test FreeBSD on bare metal, but I can’t possibly imagine the FreeBSD team releasing two different version that have such glaring performance issues so it must be something to do with FreeBSD under VMWare.

I’ve searched Google extensively regarding this issue have have come up with virtualy nothing.   My next test, Linux with the e1000 driver and no VMWare tools vmnet interfaces…

[Update]: I’m going to try Linux without VMWare tools and see how it perfoms when I get a chance, most likely tomorrow night.




  1. FreeNAS User
    April 12, 2009 at 12:10 pm

    Did you ever run the linux test without vmware tools as stated in your “Update” and see if that shows similar poor performance as FreeBSD?

  2. May 14, 2009 at 3:34 pm

    I haven’t had a chance. I’ll see what I can do this weekend.

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