Monday, October 24, 2016

Why does my debian server freeze?

I installed Debian 9 ("Stretch") in a virtual machine hosted on ESXi 6.5
The OS is up-to-date and nothing else has been installed but VMware tools.



Sometimes when I execute a command, the server will freeze and nothing can be done besides resetting the VM (the SSH server becomes unresponsive, all terminals are freezed, it doesn't show a KP or anything else)



I can reproduce the problem very easily: I just have to execute wget a couple of times and the OS will hang.



At first, I thought it could be a RAM problem. I used memtest86+ on the host and no problem was found. I also tried the debian package "memtester" which runs very well in the VM and doesn't make the OS freeze whatsoever.



/var/log/messages shows nothing special, but there's one line I don't understand:




Jul  3 13:05:57 myhost kernel: [   58.966715] TCP: ens192: Driver has suspect GRO implementation, TCP performance may be compromised.


What could be the problem and how can I debug the whole thing?



Config: 1 CPU / 4 cores - 32GB Ram - 64GB HDD

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