NFS vs Replication

[Andrea Gabellini]

Il 16/07/20 12:40, Gerald Galster ha scritto:
>> Some missing infos...
>>
>> - As load balancer I'm using a pair of keepalived with simple setup and
>> not the DNS
>> - Load balancer algorithm is "Weighted Least-Connection"
>> - About 20 domains and 3000 email
>> - I'm monitoring my backend servers with poolmon
>> - The backend servers are virtual machine (vmware) with datastore on
>> "all flash" storage
>>
>> based on yours notes, I think the better choice is Replication. Correct?
> In my experience it's best to keep complexity low because the fewer
> components you have, the fewer can fail. With replication you basically
> have two independent servers that asynchronously sync emails.

I completely agree!!!

>
> While it would work with loadbalancers/keepalived/director they are not
> necessary. If this is the way you want to go you should configure the
> loadbalancer to always send the same source-ip to the same backend
> (ip stickyness). Mailclients do open several connections in parallel
> and they should see the same data.

In my setup the load balancers do exactly this, and the director map the
same username/email (not the same source IP) to the same backend server.
Director setup is not so complex and I trust it

> With DNS this happens automatically because ips are rotated by resolvers
> and the mailclient gets the same ip for all its connections. Failover
> is builtin as mailclients just connect to the second ip when the first
> is not reachable.

I don't trust DNS load balancing. I saw too many times a client stuck
with the wrong (down) IP... This is my experience ;-)

>
> Replication works reliable with mdbox/sdbox but you should avoid maildir.

I'm using and I like Maildir. There are some documentation about to
don't use it with replication? Which are the drawbacks?

Thanks,
Andrea

>
> Best regards
> Gerald

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TIM San Marino S.p.A.
Andrea Gabellini
Engineering R&D
TIM San Marino S.p.A. - https://www.telecomitalia.sm
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