Hi List,
I have now looked all over the web to try and find best possible solution
for me... (redundant loadshared sending-only mailgw)... this is currently
what I think of doing...:
1. Setup 2 postfix servers in 2 physical different location with same
configuration (handles by our HostConfigurationManagementSys
tem).
2. DNS will be configured like:
; zone file fragment
IN MX 10 mail.example.com
.
....
mail IN A 10.10.10.100
IN A 10.10.20.100
3. Clients will use mail.example.com as server.
Only problem I see now is when one of the postfix servers dies. Clients
will still try to send mails to it as they are DNS RR'ed, but would get no
response ofcause if they hit the dead one.
(How) Do I handle this ? or will I just have to live with the time-loss,
clients connecting to dead postfix server, gives me when it has to retry ?
I can compensate a bit by setting low DNS TTL (like 15 minutes) and remove
dead DNS entry manually when our monitoring system alerts about port not
responding - but would like to implement a real redundant system if at all
possible... How do I do this - any howto I might have missed... ?
Thanks in advance :) !
~maymann
2012/3/28 Michael Maymann <mich...@maymann.org>
> Hi List,
>
> I have now looked all over the web to try and find best possible solution
> for me... (redundant loadshared sending-only mailgw)... this is currently
> what I think of doing...:
> 1. Setup 2 postfix servers in 2 physical different location with same
> configuration (handles by our HostConfigurationManagementSystem).
> 2. DNS will be configured like:
>
> ; zone file fragment
> IN MX 10 mail.example.com
> .
> ....
> mail IN A 10.10.10.100
> IN A 10.10.20.100
>
> 3. Clients will use mail.example.com as server.
>
> Only problem I see now is when one of the postfix servers dies. Clients
> will still try to send mails to it as they are DNS RR'ed, but would get no
> response ofcause if they hit the dead one.
> (How) Do I handle this ? or will I just have to live with the time-loss,
> clients connecting to dead postfix server, gives me when it has to retry ?
>
> I can compensate a bit by setting low DNS TTL (like 15 minutes) and remove
> dead DNS entry manually when our monitoring system alerts about port not
> responding - but would like to implement a real redundant system if at all
> possible... How do I do this - any howto I might have missed... ?
>
>
>
> Thanks in advance :) !
> ~maymann
>
>
> 2012/3/13 Stan Hoeppner <s...@hardwarefreak.com>
>
>> On 3/12/2012 1:29 PM, Michael Maymann wrote:
>> > Hi,
>> >
>> > Stan: thanks for your reply.
>> > I was talking about NIC bonding: http://www.howtoforge.com/nic_bonding
>> > But if that is not the way to go, then that won't matter anymore... and
>> no
>> > need for RedHat support either...
>>
>> NIC bonding isn't applicable to your dual relay host scenario.
>>
>> > I'm a simple SMTP/PostFix beginner and just trying to learn as I go
>> along -
>> > thought the mailinglist would be a good offset to get some initial
>> answers
>> > so I can start looking in the right places - first things first... :) !
>>
>> You have it backwards. The Postfix mailing list is a "last resort"
>> resource and is meant more for troubleshooting that "system design
>> assistance" or "education". You are expected to read all applicable
>> Postfix and RFC/BCP documentation and troubleshoot issues until you are
>> sure you cannot resolve them on your own. *Then* post a help query on
>> the Postfix list. It is not a teaching resource. Please don't treat it
>> as such.
>>
>> > If RR DNS is the way forward, then I guess I would need to configure:
>> >
>> > ; zone file fragment
>> > IN MX 10 mail.example.com.
>> > ....
>> > mail IN A 192.168.0.4
>> > IN A 192.168.0.5
>> >
>> >
>> > and point all my MUA's to mail.example.com
>> >
>> > Just to try and understand better how this communication would be
>> working:
>> > 1. Does the MUAs then just retry if it doesn't get answer from one of
>> the
>> > MTAs ?
>> > 2. If so, will this then always generate a new nslookup / will it use a
>> > cache / do I need to configure this on the MUA's ?
>> > 3. Is there a default number of retries (and does this differentiate
>> from
>> > MUA to MUA) or are they just queued forever on the MUAs until properly
>> > delivered to a responsive MTA ?
>>
>> See the bind manual, or the manual of whichever DNS server daemon you
>> happen to be using, and other applicable guides to round robin DNS.
>>
>> --
>> Stan
>>
>
>
