[pve-devel] Quorum problems with NICs Intel of 10 Gb/s and VMsturns off

[Michael Rasmussen]

On Wed, 24 Dec 2014 12:49:39 +0100 (CET)
Alexandre DERUMIER <aderumier at odiso.com> wrote:

> 
> >>Moreover, i have doubts over these 3 options (Bios Hardware): 
> >>- OS Watchdog timer (option available in all my servers) 
> 
> you can use it if you don't use fencing from proxmox. I'll restart the server in case of a kernel panic for example.
> 
> 
If would change recommendation to 'must disable in case of using
fencing'

> >>- I/OAT DMA Engine ( i am testing with two servers DELL R320, each server 
> >>with 2 NICs Intel of 1 Gb/s, 4 ports each one) 
> Don't known too much about this one.
> 
An old Intel-only way to increase nic performance by offloading memory
copies to DMA. Experimental support in VmWare 3.5 but since 4.x this
support has been removed:
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1003712

The Linux kernel has supported it since 2006 but if this is the case
for 2.6.32 I have no idea.

Since VmWare has dropped support I guess it means it could cause
problems for VMs. Maybe you face the same problems like hardware
checksum offloading which has to be disabled for proper net speed
(avoid massive package drop)

> 
> Maybe it's related to turbo core, with some intel processor.
> Generally, I recommand to turn this off, because it's dynamically shutdown some cores to speedup other cores.
> And virtualization don't like this too much, because of changing clock frequency. (bsod under windows)
> 
> 
Turbo core is also present on AMD multi core processors.

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Michael Rasmussen

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