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Xpenology ESXI CPU I/O Wait reaches100% during file transfer


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I am a newbie here. I just bought a N54L and have installed esxi on a USB key which is plugged in the internal USB port always. I then installed xpenology DSM 5.0-4493.


Currently I have 1x2TB WD Red NAS hdd installed. I created a SHR volume and was trying to copy a 900mb video file from a windows 7 machine.


The transfer rate starts at 100mbps but suddenly the CPU I/O wait reaches 100% (see attachment pls) :sad: and the transfer freezes until the wait comes down


Can somebody please help what could be causing this issue?


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  • 1 year later...



First of all, TY shteve !! :grin:

This bios-tip helped me fix the problem that when tranmission started to download PLEX would stall.


New healthy graph (used to be like neels graph):


Notice the downloading speed in the upper right (it used to never go above 1MB/sec, if it reached 1MB/sec my PLEX would start to get in trouble (stopping playback) and CPU IOwait would be through the roof.


I achieved this by setting the following in the VM's BIOS:

RIfbaik.jpg (Under advanced go to "Cache memory" and enable memory cache, then set all to "write through" and others that dont have this option to "write protect"


To check if cache is now on, check with the following:

CmNDliB.jpg (dmesg | grep -i cache)


Notice that after a reboot the settings in the VM's bios go back to:


But after reboots with the dmesg|grep -i cache < cache continues to work properly!


I hope this makes someones as happy as me that PLEX stops video when downloads start in the backgroun:)



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