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Haefele
Contributor
Contributor

ESXI 6.7 Slow Download speed (but fast network/disks)

So here is one that I can't seem to figure out.

I recently spun up a new 6.7 host on new hardware and am getting very bad download speed from the internet (either updates, or just file downloads from a browser.) downloads will quickly drop from multiple MB/s down to 4-8kbps within seconds, and then just stay there on multiple VM's both windows and linux.

It is not a slow mirror issue, It happens with all files on the VM, and I downloaded the same file from a non-VM machine:

novm.JPG

from the same mirror that I did from a VM:

vm.JPG

If I transfer files to/from a shared drive on one of the VM's I get >100MBps (which maxes out the 1Gbps NIC) sustained throughout the transfer, so it doesn't seem to be a network or disk issue.

samba.JPG

If I run a browser speedtest or iPerf test on a VM, it easily hits a good speed, with iPerf showing 800+ Mbps up and down to public servers, while downloads still seem to stall at 10kbps.

speed.JPG

At the same time streaming video on a VM has no issues (and youtube stats show 100+mbps 'connection speed) It's only when downloading a file that the issue seems to crop up.

youtubt.JPG

I have been running a Ubuntu install and it has been trying to download updates for over an hour (with 84 minutes remaining on the timer for downloading a language pack) on a WAN connection where the bottleneck is the 1Gbps connection to the server.

I see no impact on the VM's performance wise (installing already downloaded files, running tasks, booting etc) I just can't download files.

Torrents run at full speed:

torrent.JPG

But trying to wget a file shows things go slow so it is not just a browser thing:

wget.JPG

VMTools are installed

Anyone seen anything like this before? It is a new one for me.

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6 Replies
Haefele
Contributor
Contributor

And yes I realize all of these examples are of the same file.  Just to reiterate, on the VM's this is happening with all downloads regardless of source on the VM's

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Haefele
Contributor
Contributor

More information:

Issue seems to be TCP related, but I don't know the cause.

Getting vsish stats for the interfaces show no dropped packets:

netstats.JPG

But Wireshark analysis shows periods of time where it is only receiving 1-3 packets a second interspersed between short periods of normal function:

bad.JPG

So I am still not sure what is going on

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Haefele
Contributor
Contributor

Slow speed can be observed directly on the ESXI server with wget.

NIC is Intel 4P x540/i350 rNDC, using native VMW drivers

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danfratamico
Contributor
Contributor

What was the solution? I am have the same exact issue, except when I run speed test on one of my VMs, my download speed is very slow but upload is full speed.

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nystudent
Contributor
Contributor

same here

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peetz
Leadership
Leadership

Please do not reply to old threads that are months and years old.

"same here" is nothing that anyone can respond to in a helpful manner.

Open a new thread instead and provide a description of your issue, system setup etc.

Moderator: Locking thread.

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