[Info-vax] How would you load balance excess webserver traffic between multiple OpenVMS servers?

[Dirk Munk]

Arne Vajhøj wrote:
> On 1/13/2021 5:36 PM, Dirk Munk wrote:
>> ultr... at gmail.com wrote:
>>> On Wednesday, January 13, 2021 at 9:03:50 AM UTC-5, Dirk Munk wrote:
>>>> D W wrote:
>>>>> There are MULTIPLE different approaches to doing this. Most involve 
>>>>> HTTP (web) cookies and may involve DNS round robin load balancing 
>>>>> or load balancers.
>>>>>
> 
>>>> You could use a DNS server with round robin functionality. That way you
>>>> can use multiple IP interfaces on one VMS server, as well as more VMS
>>>> servers.
>>>>
> 
>>> do you mean like port forwarding or a www1. type of solution? I'm 
>>> going to implement DNS services on their system just in case for 
>>> redundancy.
>>
>> No, round robin is very simple.
>>
>> let's say you have 4 vms ip interfaces for you server, they can be on 
>> one server (4 interfaces) or two servers (2 x 2 interfaces) or 4 
>> servers. The IP addresses are 10.0.0.1 , 10.0.0.2 , 10.0.0.3 , and 
>> 10.0.0.4 , so very simple.
>>
>> With a round robin dns server, you will create a host www.myvms.com , 
>> and give that host all four IP addresses.
>>
>> When you open a connection to www.myvms.com , it will go to 10.0.0.1 . 
>> A second later it will go to 10.0.0.2 , and again a second later to 
>> 10.0.0.3 , and then to 10.0.0.4. , and finally back to 10.0.0.1 , and 
>> so on.
> 
> The key question is what happens if 10.0.0.2 is down.
> 
> Arne
> 

Good point. A good round-robin DNS server would notice that.

In fact it seems there are round-robin DNS servers that can take the 
load of a server into account, skipping severely loaded severs for 
instance. Don't know how that actually works.