You can do it using replication,

https://wiki.dovecot.org/Replication

but since you have no staging/test environment, I would advice you to get one.

Aki

On 09/01/2020 18:45 Kishore Potnuru kishore.reachme@gmail.com wrote:

Thank you Aki for the reply. 

But I cannot disturb the version at present as it is a live server and thousands of emails will circulate every hour.

Could you please suggest me how to create HA/resilience for the existing environment. I have another server ready with the similar configuration. Please provide any steps/link for me to proceed on this? It will be a great help to me.

Thanks, Kishore

On Thu, Jan 9, 2020 at 4:33 PM Aki Tuomi aki.tuomi@open-xchange.com wrote:

...

...

On 09/01/2020 18:25 Kishore Potnuru kishore.reachme@gmail.com wrote:

Hi Dovecot team, 

I need help in configuring HA/resilence for my dovecot (POP3/IMAP) server.

I have one RHEL Linux POP3/IMAP server with Dovecot version 2.2.10. I also installed the postfix(version: 2.6.6) in it. At present it have around 10 domains and each domain is having around 20 email boxes. It has very simple configuration.

User's reading the email via some internal applications/Outlook.

I would like to create resilience/HA for this environment. Could you please suggest me, what is the easiest way to achieve this?

If any one can suggest step by step that will be more helpful to me.

Thanks, Kishore

You could consider using more recent version of dovecot. 2.2.10 is already over 5 years old.

Aki

On 10.1.2020 9.00, Emmanuel Dreyfus wrote:

On Thu, Jan 09, 2020 at 06:51:36PM +0200, Aki Tuomi wrote:

...

You can do it using replication, https://wiki.dovecot.org/Replication Last time I tried, it did not work with mbox. Did that change? The document does not tell about the format.

Replication is not supported with mbox. Most features are not.

Aki

On 10 Jan 2020, at 9.20, Emmanuel Dreyfus manu@netbsd.org wrote:

On Fri, Jan 10, 2020 at 09:07:24AM +0200, Aki Tuomi wrote:

...

Replication is not supported with mbox. Most features are not.

It would be nice if the document about replication could tell what setup works.

First step in setting up HA system would be to migrate away from mbox.

Sami

Hello,

you need to "clone" the first server, change the ip address, mount the same maildir storage and use some mechanism to share the accounts database.

Then you need to put a TCP load-balancer in front of the servers an you are good to go. This is the easiest solution if you already have in the network an appliance that can do LB. For instance if you already have a firewall with that function.

Another solution is to make a cluster with corosync/pacemaker out of the two servers:

https://www.digitalocean.com/community/tutorials/how-to-create-a-high-availa...

https://linuxacademy.com/blog/linux-academy/configure-a-failover-cluster-wit...

On 1/10/20 7:16 PM, Kishore Potnuru wrote:

Thank you all for the replies....

I have the test environment with the same configuration. But I have been asked to go with same environment for HA/Resilience in Live.

Yes, I have only one Live server. It is configured in "Maildir" format. The data stores on a Network / Shared Storage (But definitely not local disk, its a mount point).

I have been asked to create a HA/Resilience for this environment. They gave me another server with same ram/cpu/os and I need to configure the dovecot on it.

Please provide your suggestions/steps as I am new to this kind of environment.

Is it possible, when any email comes to any one or both of the two servers, how it will be read by the user from Outlook? How to create the environment?

Thanks, Kishore Potnuru

On Fri, Jan 10, 2020 at 7:55 AM Sami Ketola mailto:sami.ketola@dovecot.fi> wrote:

> On 10 Jan 2020, at 9.20, Emmanuel Dreyfus <manu@netbsd.org
<mailto:manu@netbsd.org>> wrote:
>
> On Fri, Jan 10, 2020 at 09:07:24AM +0200, Aki Tuomi wrote:
>> Replication is not supported with mbox. Most features are not.
>
> It would be nice if the document about replication could tell
> what setup works.


First step in setting up HA system would be to migrate away from mbox.

Sami

-- Best regards, Adrian Minta

Yes, but it works for small systems if you set IP source address persistence on LB or even better, if you set priority to be Active/Standby. I couldn't find a good example with dovecot director and backend on the same server, so adding another two machines seems overkill for small setups.

If someone has a working example for this please make it public !

Quote from https://wiki2.dovecot.org/Director

"Director and Backend in same server (broken) NOTE: This feature never actually worked. It would require further development to fix (director would need to add "proxy" field to extra fields and notify auth that the auth_request can be freed)."

Also:

https://dovecot.org/pipermail/dovecot/2012-May/135600.htm

https://www.dovecot.org/list/dovecot/2012-June/083983.html

On 1/10/20 8:09 PM, Aki Tuomi wrote:

Also you should probably use dovecot director to ensure same user sessions end up on same server, as it's not supported to access same user on different backends in this scenario.

Aki

...

On 10/01/2020 19:49 Adrian Minta adrian.minta@gmail.com wrote:

Hello,

you need to "clone" the first server, change the ip address, mount the same maildir storage and use some mechanism to share the accounts database.

Then you need to put a TCP load-balancer in front of the servers an you are good to go. This is the easiest solution if you already have in the network an appliance that can do LB. For instance if you already have a firewall with that function.

Another solution is to make a cluster with corosync/pacemaker out of the two servers:

https://www.digitalocean.com/community/tutorials/how-to-create-a-high-availa...

https://linuxacademy.com/blog/linux-academy/configure-a-failover-cluster-wit...

On 1/10/20 7:16 PM, Kishore Potnuru wrote:

...

Thank you all for the replies....

I have the test environment with the same configuration. But I have been asked to go with same environment for HA/Resilience in Live.

Yes, I have only one Live server. It is configured in "Maildir" format. The data stores on a Network / Shared Storage (But definitely not local disk, its a mount point).

I have been asked to create a HA/Resilience for this environment. They gave me another server with same ram/cpu/os and I need to configure the dovecot on it.

Please provide your suggestions/steps as I am new to this kind of environment.

Is it possible, when any email comes to any one or both of the two servers, how it will be read by the user from Outlook? How to create the environment?

Thanks,

Kishore Potnuru

On Fri, Jan 10, 2020 at 7:55 AM Sami Ketola sami.ketola@dovecot.fi wrote:

...

...

On 10 Jan 2020, at 9.20, Emmanuel Dreyfus manu@netbsd.org wrote:

On Fri, Jan 10, 2020 at 09:07:24AM +0200, Aki Tuomi wrote:

...

Replication is not supported with mbox. Most features are not.

It would be nice if the document about replication could tell what setup works.

First step in setting up HA system would be to migrate away from mbox.

Sami

-- Best regards, Adrian Minta

-- Best regards, Adrian Minta

My own personal setup is a 3-node system using three cheap VPS'. I also helped to set the same thing up for a previous company using proper systems, this was handling customer email.

Everything possible is kept in mariadb with galera for master-master replication. Two main mail nodes with dovecot/nginx/roundcube/spamassassin/etc and a third as a mariadb quorum node. Dovecot uses replication to keep the encrypted mailstores in sync.

This way there is no need for HA storage - you're relying on replication. Oh, and the replication all happens over a tinc vpn mesh network, but would work equally well over zerotier or whatever.

I have an ansible playbook to set the whole thing up automagically. I'm working on cleaning it up and documenting it so others can use it as well. So long as you have ssh key'd access to 3 nodes, it will build the entire setup.

I'll put it up on github in a few weeks. NOTE: this is built for MY needs. It might not meet your needs. But when it's ready(ish) you're welcome to try it out. For example, it's not true HA - you have to hit one node or the other. If you control your own DNS you could set up round-robin for a mail.yourdomain.com rather than using mail1.yourdomain.com and mail2.yourdomain.com. For me, I don't bother.

Dean.

On 2020-01-11 3:50 am, Jean-Daniel wrote:

If you just want active/standby, you can simply use corosync/pacemaker as other already suggest and don’t use Director. I have a dovecot HA server that uses floating IP and pacemaker to managed it, and it works quite well.

The only real hard part is having a HA storage. You can simply use a NFS storage shared by both servers (as long as only one has the floating IP, you won’t have issue with the same client accessing it from both servers), but the storage will then be a single point of failure. You may have both server have their own storage and sync it using dovecot replicator (I have never tried, so I can’t say for sure), or have an other layer taking care of the storage sync (like DRDB).

While drdb is fine to sync dovecot storage, it may not be enough if you really want HA and have other services (postfix, rspamd, …) running on that server, as you may need to also have the postfix queues (or other data) sync on both servers.

...

Le 10 janv. 2020 à 21:12, Adrian Minta adrian.minta@gmail.com a écrit :

Yes, but it works for small systems if you set IP source address persistence on LB or even better, if you set priority to be Active/Standby. I couldn't find a good example with dovecot director and backend on the same server, so adding another two machines seems overkill for small setups.

If someone has a working example for this please make it public !

Quote from https://wiki2.dovecot.org/Director

"Director and Backend in same server (broken) NOTE: This feature never actually worked. It would require further development to fix (director would need to add "proxy" field to extra fields and notify auth that the auth_request can be freed)."

Also:

https://dovecot.org/pipermail/dovecot/2012-May/135600.htm

https://www.dovecot.org/list/dovecot/2012-June/083983.html

On 1/10/20 8:09 PM, Aki Tuomi wrote:

...

Also you should probably use dovecot director to ensure same user sessions end up on same server, as it's not supported to access same user on different backends in this scenario.

Aki

...

On 10/01/2020 19:49 Adrian Minta adrian.minta@gmail.com wrote:

Hello, you need to "clone" the first server, change the ip address, mount the same maildir storage and use some mechanism to share the accounts database.

Then you need to put a TCP load-balancer in front of the servers an you are good to go. This is the easiest solution if you already have in the network an appliance that can do LB. For instance if you already have a firewall with that function.

Another solution is to make a cluster with corosync/pacemaker out of the two servers:

https://www.digitalocean.com/community/tutorials/how-to-create-a-high-availa...

https://linuxacademy.com/blog/linux-academy/configure-a-failover-cluster-wit...

On 1/10/20 7:16 PM, Kishore Potnuru wrote:

...

Thank you all for the replies....

I have the test environment with the same configuration. But I have been asked to go with same environment for HA/Resilience in Live. Yes, I have only one Live server. It is configured in "Maildir" format. The data stores on a Network / Shared Storage (But definitely not local disk, its a mount point). I have been asked to create a HA/Resilience for this environment. They gave me another server with same ram/cpu/os and I need to configure the dovecot on it. Please provide your suggestions/steps as I am new to this kind of environment. Is it possible, when any email comes to any one or both of the two servers, how it will be read by the user from Outlook? How to create the environment?

Thanks, Kishore Potnuru On Fri, Jan 10, 2020 at 7:55 AM Sami Ketola sami.ketola@dovecot.fi wrote:

...

> On 10 Jan 2020, at 9.20, Emmanuel Dreyfus manu@netbsd.org wrote: > > On Fri, Jan 10, 2020 at 09:07:24AM +0200, Aki Tuomi wrote: >> Replication is not supported with mbox. Most features are not. > > It would be nice if the document about replication could tell > what setup works. First step in setting up HA system would be to migrate away from mbox. Sami

Newest version available on el7 is 2.2.36. You should be having no problems with updating minor versions. Or clone the production environment to a test environment and test the upgrade.

-----Original Message----- From: Kishore Potnuru [mailto:kishore.reachme@gmail.com] Sent: 09 January 2020 17:45 To: Aki Tuomi Cc: dovecot@dovecot.org Subject: Re: Dovecot HA/Resilience

Thank you Aki for the reply.

But I cannot disturb the version at present as it is a live server and thousands of emails will circulate every hour.

Could you please suggest me how to create HA/resilience for the existing environment. I have another server ready with the similar configuration. Please provide any steps/link for me to proceed on this? It will be a great help to me.

Thanks, Kishore

On Thu, Jan 9, 2020 at 4:33 PM Aki Tuomi aki.tuomi@open-xchange.com wrote:

> On 09/01/2020 18:25 Kishore Potnuru <kishore.reachme@gmail.com> 

wrote: > > > Hi Dovecot team, > > I need help in configuring HA/resilence for my dovecot (POP3/IMAP) server. > > I have one RHEL Linux POP3/IMAP server with Dovecot version 2.2.10. I also installed the postfix(version: 2.6.6) in it. At present it have around 10 domains and each domain is having around 20 email boxes. It has very simple configuration. > > User's reading the email via some internal applications/Outlook. > > I would like to create resilience/HA for this environment. Could you please suggest me, what is the easiest way to achieve this? > > If any one can suggest step by step that will be more helpful to me. > > Thanks, > Kishore

You could consider using more recent version of dovecot. 2.2.10 is 

already over 5 years old.

Aki