<div dir="auto"><div><br><div class="gmail_extra"><br><div class="gmail_quote">On Dec 1, 2017 5:50 PM, "Wesley Stewart" <<a href="mailto:wstewart3@gmail.com">wstewart3@gmail.com</a>> wrote:<br type="attribution"><blockquote class="quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">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 "<b>Turn off Windows Write-Cache buffer flushing on the device</b>"<div><br></div><div>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.</div></div></blockquote></div></div></div><div dir="auto"><br></div><div dir="auto">It's safe until you have an unplanned power failure, and then some undetermined amount of data might be lost. </div><div dir="auto">Y. </div><div dir="auto"><br></div><div dir="auto"><div class="gmail_extra"><div class="gmail_quote"><blockquote class="quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="elided-text"><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Nov 30, 2017 at 10:39 PM, Wesley Stewart <span dir="ltr"><<a href="mailto:wstewart3@gmail.com" target="_blank">wstewart3@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><div><div><div><div><div><div>I was curious if anyone else has seen this or had any suggestions.<br><br></div>I have recently began playing around with my two servers (Freenas Box and oVirt box) and their 10Gb Ethernet ports.<br><br></div>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.<br><br></div><b>For my first test</b>,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!<br><br></div><b>For my second test</b>, 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...<br><br></div>Writing TOO the NAS worked about the same. Perhaps a little slower but at least had a steady 250-300 MB/s.<br><br></div>Writing to the Windows Guest had a very "Fast and then slow, fast and then slow" type of throughput. I took a few screenshots:<br><br></div>(Writing TO the NAS was fairly consistent)<br><div><br><img src="cid:ii_160102257a9592b6" alt="Inline image 1" style="margin-right:0px" width="344" height="182"><br><a href="https://i.imgur.com/jWNNvfp.png" target="_blank">https://i.imgur.com/jWNNvfp.pn<wbr>g</a><br><br></div><div><br></div><div>(Writing TO the Windows Guest on NVMe storage)</div><div>Sometimes these hit the <b>low 10-20 MB/s</b> during the transfer.<br></div><div><img src="cid:ii_1601023b2c9c1c59" alt="Inline image 2" style="margin-right:0px" width="357" height="193"><br><a href="https://i.imgur.com/aizG6n0.png" target="_blank">https://i.imgur.com/aizG6n0.pn<wbr>g</a><br><br></div><div><img src="cid:ii_1601023deccd1094" alt="Inline image 3" style="margin-right:0px" width="342" height="179"><br><a href="https://i.imgur.com/AjRpR0K.png" target="_blank">https://i.imgur.com/AjRpR0K.pn<wbr>g</a></div><div><br></div><div><br></div><div><br></div><div><br><br><br></div></div>
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