[olug] Need assistance from apache gurus

[Jay Bendon]

How do TCP settings compare from centos5 to centos6?

Are you getting a lot of syn drops? (netstat -s |grep -i dropped)

NoFiles limits reasonable?

sanity check your somaxconn and tcp_max_syn_backlog and rmem wmem, and
nf_conntrack_max (if using iptables) settings for your application (and
compare to centos5)

Just spitballing some of the common reasons for connectivity issues under
loads

--Jay

On Mon, Sep 19, 2016 at 2:15 PM, Jon Larsen <jon at jonlarsen.us> wrote:

> I have a weird issue on my plate.
>
> I have three apache web servers behind an ldirector load balancer running
> centos 5.x on VMWARE.  I've built three new centos 6.x web server VMs to
> replace them.
>
> I used the same apache configs, as the apache versions don't change much
> between 5 and 6.
>
> I'm encountering intermittent network disconnects when I use the new three
> centos 6 systems in production, forcing me to back peddle to the older cent
> 5 systems.
>
> The disconnects appear at random, and no concurrent high CPU load.
>
> The disk scheduler is already set for deadline, and I'm using the suggested
> VMware 'vmxnet3' nic adapters.
>
> I've tried several profiles of prefork settings, but encounter the same
> issue.
>
> Currently, they are set to:
>
> StartServers 100
> MinSpareServers 30
> MaxSpareServers 40
> ServerLimit 220
> MaxClients 220
> MaxRequestsperChild 2000
>
> Any ideas?
>
> Jon L.
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