AMS Clustering

[Pugglewuggle]

I dont' know what scope of customer you're targeting AMS for, but I can tell you that an AMS clustering scheme would be a very useful feature in preventing downtime. This would (naturally) allow two or more AMS servers to run as a team in case of an outage on one server so the whole email system doesn't go down.

I realized just how useful this would be the other day when our server went offline for over 24 hours.

Ideally, AMS would keep a version tracking database (for stateful file tracking) to keep track of the latest version of files and if one is written or update that file would then be replicated over to the other servers in the cluster.

I'm sure this is as complicated to code as it sounds. If you do ever decide to try this, let me know. I've got a bit of experience in replication and HA setups with both servers and networking equipment where stateful failover is implemented.

[Code Crafters]

AMS already supports clustering for service load balancing (e.g. SMTP on one mail server, mail access services on another etc.), backup mail servers (backup MX with forwarding capabilities) and also load sharing of the same services on multiple servers using a network drive to share the settings.

[m1byo]

How would that be configured?

Is that just setting the accounts directory to a network drive which a different AMS installation also has the same accounts directory?

What about file sharing/access issues?

[Pugglewuggle]

Agreed on the sharing issues... how does it handle locking with multiple servers accessing files? I suppose the sync folder would then hold a randomly names scratch file for whatever's being modified?

So you're saying the clustering is scalable across multiple front-end mail servers?! Meaning: If I assign 2 public IPs to two AMS servers and have both of those servers in public DNS under the same host name (for round robin LB), then it will work if they are sharing a config folder on a file share? How does this work with an ODBC based setup? I suppose the ODBC source would just be hosted on another machine across the network as well (SQL Server)?

Does AMS support clustering as in hot failover? Meaning that two or more systems are accessed by one IP addresss and are joined together by NIC in addition to being connected to a switch with another NIC and stateful session information is transferred over the NIC pair so if one server drops no connections are lost and the TCP connection state stays intact?

Sorry I'm just ridiculous.

[Code Crafters]

File access issues are dealt with internally by AMS and you don't need to worry about how this is full achieved but the sync files and other programming thread sync technologies help control this.

Yes, you can just have multiple AMS servers sharing one account directory on a network drive to allow any of them to access the accounts. Each mail server will have its own connections and if the mail server fails, the connection will be lost but the other mail server will still be there to pick up future connections. Of course, you have to set up the MX records so that 2 mail servers with the same priority are available on the DNS records.