I have been fiddling with the drive settings in the windows guest and have been able to fix a lot of the issue. I went into Device manager -> Disk Drives -> (right click) QEMU QEMU HARDDISK -> Policies and checked "*Turn off Windows Write-Cache buffer flushing on the device*"
I am not sure how safe this is to do in a virtual machine, but my 10Gb transfer speed is now much more stable. Occasionally it dips to the low 100 MB/s or so, but generally stays at 200-300 MB/s. On Thu, Nov 30, 2017 at 10:39 PM, Wesley Stewart <wstewa...@gmail.com> wrote: > I was curious if anyone else has seen this or had any suggestions. > > I have recently began playing around with my two servers (Freenas Box and > oVirt box) and their 10Gb Ethernet ports. > > I can access the Freenas SMB share over the 10Gb port without issue and I > have been playing around with the capabilities. After finding out that my > Linux Raid (MDADM) mirror is having horrible write performance, I decided > to plug in an NVMe drive that I had lying around and check out its > performance. > > *For my first test*,I added the NVMe drive as a passthrough device to a > Windows guest and was able to transfer to and from Freenas box without > issue. Speeds were typically ~350-400 MB/s but could drop down to 250 MB/s > or so, and would top out around 525 MB/s, pretty slick! > > *For my second test*, I decided to mount the NVMe drive on the CentOS > ovirt host and make it a local datastore. I migrated my Windows Guest to > it, and decided to test and see what sort of transfer speeds I got and saw > some weird results... > > Writing TOO the NAS worked about the same. Perhaps a little slower but at > least had a steady 250-300 MB/s. > > Writing to the Windows Guest had a very "Fast and then slow, fast and then > slow" type of throughput. I took a few screenshots: > > (Writing TO the NAS was fairly consistent) > > [image: Inline image 1] > https://i.imgur.com/jWNNvfp.png > > > (Writing TO the Windows Guest on NVMe storage) > Sometimes these hit the *low 10-20 MB/s* during the transfer. > [image: Inline image 2] > https://i.imgur.com/aizG6n0.png > > [image: Inline image 3] > https://i.imgur.com/AjRpR0K.png > > > > > > >
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