Clustering is a way for several servers to act as one. One InterWorx Control Panel box acts as the Director (Master), and the other InterWorx boxes are set as Nodes (Slaves). The nodes mount the /home partition of the director, so when someone comes to a site on the Director it will be load balanced across all of the boxes. All data continues to be stored on the Director server.
Yes, since all data is stored on one server, in the event of a hard drive crash the whole thing goes down. Users may wish to consider a Hardware RAID setup for redundancy, as well as some sort of nightly off server backup.
The most common use for clustering is to combine the resources of several servers to power one or more popular and/or processor intensive sites.
It can also be used to group more than one server together for DNS purposes. Since all of the sites are on one box, you only need one set of name servers.
The clustering/load balancing setup for InterWorx Control Panel boxes *will* work in NAT'd setup UNDER THE FOLLOWING CONDITIONS:
You must use STATIC NAT, where there is a one-to-one correspondence between external and internal IP's.
You can use InterWorx Control Panel in an un-clustered setup behind NAT (any NAT) without problems, but the clustered/load balanced version will require static NAT.
No, CentOS and Red Hat Enterprise are essentially the same operating system (based upon the same source code), so clustering DOES work on RHEL 4.x as long as NAT is set up, but we do our internal testing on CentOS 4.x and it is the recommended platform.
you also need to make some changes to your file system in order to work:
/home/vpopmail needs to be moved to /var/vpopmail
/home/interworx needs to be moved to /usr/local/interworx
And symlinks must be created from the old to the new locations.
(This is ONLY an issue for serves UPDATING to 2.1.0 from an earlier version. The new version of the install script will do this automatically.)
The screens to control load balancing do not appear unless NAT is also properly configured. When this is the case you will see a Clustering category on the main menu.
General Clustering FAQ
What Is Clustering?
Clustering is a way for several servers to act as one. One InterWorx Control Panel box acts as the Director (Master), and the other InterWorx boxes are set as Nodes (Slaves). The nodes mount the /home partition of the director, so when someone comes to a site on the Director it will be load balanced across all of the boxes. All data continues to be stored on the Director server.
What are the benefits of clustering?
The chief benefit of clustering is that that you have the resources of several servers working as one.
Another benefit is that these same resources appear to be one server even from the DNS standpoint so you only need one set of name servers.
Are there any drawbacks of clustering?
Yes, since all data is stored on one server, in the event of a hard drive crash the whole thing goes down. Users may wish to consider a Hardware RAID setup for redundancy, as well as some sort of nightly off server backup.
What are some implementations of clustering?
The most common use for clustering is to combine the resources of several servers to power one or more popular and/or processor intensive sites.
It can also be used to group more than one server together for DNS purposes. Since all of the sites are on one box, you only need one set of name servers.
Does InterWorx Control Panel support High Availability (HA) Clusters?
No, not at this time, however a future release will support this. There is NO ETA on this feature.
Clustering Setup FAQ
Will InterWorx Control Panel Clustering work with a NAT setup?
The clustering/load balancing setup for InterWorx Control Panel boxes *will* work in NAT'd setup UNDER THE FOLLOWING CONDITIONS:
You can use InterWorx Control Panel in an un-clustered setup behind NAT (any NAT) without problems, but the clustered/load balanced version will require static NAT.
Search for: “Basic NAT vs port number translation” and it gives a good description.
If we only had one public IP, could we setup a cluster service? Would the service run on private IPs? The setup would be with one public IP and behind it, imagine five servers doing load balancing and clustering. Would this be possible?
Yes, one public IP is fine. The cluster nodes on the internal network must reside on the same network segment.
I've noticed that you say that CentOS 4.x is required for clustering. Does this mean that I can't use Red Hat Enterprise 4.x?
No, CentOS and Red Hat Enterprise are essentially the same operating system (based upon the same source code), so clustering DOES work on RHEL 4.x as long as NAT is set up, but we do our internal testing on CentOS 4.x and it is the recommended platform.
Clustering Nodes FAQ
With clustering, does each server need its own InterWorx license?
Yes, since each box (Cluster Manager and Node) has a copy of InterWorx Control Panel installed, each needs its own unlimited domain license.
Can I add and remove Nodes to the cluster transparently?
Yes. The end user will not see any difference other than a possible performance drop if the load is high.
Load Balancing FAQ
I thought that InterWorx 2.1.0 had Load Balancing on it, but I don't see it on the menu?
You need the following three conditions:
And symlinks must be created from the old to the new locations.
(This is ONLY an issue for serves UPDATING to 2.1.0 from an earlier version. The new version of the install script will do this automatically.)
The screens to control load balancing do not appear unless NAT is also properly configured. When this is the case you will see a Clustering category on the main menu.