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Showing posts from February, 2018

NVENC & Framebuffer Sizing

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Coming from K2 based servers, we did  not have the GPU monitoring capabilities or NVENC in our existing VDI servers.  That being said, the new monitoring features available on Maxwell and Pascal series GPUs have exposed some interesting sizing considerations when using NVENC. As we've been putting the new Tesla P4 based servers into production, we've noticed much higher GPU usage at idle than expected.  Initially, to compensate, we've increased the framebuffer profile from "P4-1Q" to "P4-2Q" and see if that solved the performance issues and high framebuffer usage.  Indeed it did, so I went searching for why! Turns out (and this make total sense) that the encode process is using additional video RAM over what it was using without NVENC.  Using RDanalyzer I looked at the encoder memory usage for Single, Dual, and Quad monitor systems using both CPU and GPU encode.  See the table below: Takeaways: The NVENC vRAM/FB usage increase is approximat

Time issues on R740 & 7.2/7.3

We have had issues on our two R740s with clocks becoming out of sync even with NTP servers setup.  Our first assumption was that we had set something up wrong... These were good references to rule that out and show we had an actual issue: NTP Sync: https://support.citrix.com/article/CTX226572 Tips by Tobias: https://discussions.citrix.com/topic/381709-xenserver-70-and-ntp/ Restarting the NTP client synced the time, but within a few days the times would both be wrong (slow) by dozens of minutes and sometimes even up to an hour or more.  Both hosts would also be significantly different.  While one would be off by 45 minutes the other might be off by an hour and 15 minutes.  This was obviously something more and needed to be escalated to support. Here is what came from the support call: The agent changed the current clock source from tsc to xen by running the following at the console. echo "xen" > /sys/devices/system/clocksource/clocksource0/current_clocksource

Dell R740 issues with XenServer 7.1/7.2 (Continued)

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My previous post ( https://allthingstechsmb.blogspot.com/2017/11/dell-r740-issues-with-xenserver-7172.html ) indicated I was setting up 2 new R740s for our upgraded CAD/Revit VDI deployment.  We've had a few issues/learning experiences.  This is an extension of that posts with things I've found out since and new issues that have come up.  In addition, XenServer 7.3 solved one of our issues. Storage Controller - H740p This is a continuation of the issue with the H740p driver from the previous post.  This issue was resolved in XenServer 7.3, with the supported driver being included in the 7.3 install media. Crash Dumps when booting in UEFI mode While they have worked perfectly, I have been seeing crash dumps reported in XenCenter on every reboot when XenServer is installed in UEFI mode.  If you boot with BIOS and install, there are no Crash Dumps. Per Rody Kossen (@R_Kossen), This will be fixed in XenServer 7.4, which is unofficially set to be released later this mont