Monday, July 28, 2008

Lotus Notes/Domino superior availability

This past weekend we had an issue with one of our primary systems which hosts 2 primary Domino mail servers. The system went down completely taking down all hosted Domino partitions with it. Since we have clustered Domino servers this was a non-issue. The cluster nodes for these primary Domino servers are on a totally separate system. Specifically a separate machine, disk, and location. Since the Notes client is cluster aware it failed over to the cluster nodes automatically. The most a user has to do is close their mail file (not restart Notes) and re-open it.

This is something Outlook and Exchange cannot natively do. Outlook is in no way cluster aware so there is no automatic failover. It relies on DNS to point it to the Exchange server. Exchange has 2 clustering methods neither of which is as good as Domino. You can use Windows clustering with Exchange which requires shared disk. If your disk goes or the storage group gets corrupted then this type of clustering does no good. Exchange 2007 has continuous cluster replication now which is simply transaction log shipping. This cluster replication is supported only on the same LAN meaning local. If the local LAN or building power goes down, so does the cluster.

With either method the DNS needs to be updated or a server needs to assume the previous server IP address in order for Outlook to work. This takes time and is not immediate.

This is why there is a whole third party industry built around keeping Exchange available. This third party industry and associated extra cost doesn’t exist for Domino. Domino provides the best of breed service out of the box.

Before the flames start about how Notes sucks this post is specific to clustering. Lotus Domino is far superior when it comes to availability options. Outlook may be prettier but it doesn’t do much good when you can’t send and receive e-mail.

2 comments:

Craig said...

Yeah, Notes sucks.

It just sucks LESS, far less, than the alternatives.

David Price said...

From what I understand failing back in an Exchange 2007 cluster is difficult.