System-Level Fault Tolerance (Clustering/Network Load Balancing) - Restoring Cluster Nodes After a Cluster Failure

(Page 22 of 26 )

Cluster nodes can be restored after a cluster failure using a combination of the previously described restore steps, with a few added steps. If each cluster node can start but Cluster Service cannot start on any node, there is most likely a problem with the quorum drive or quorum data.

To restore the cluster nodes in this situation, follow these steps:

1. To restore the quorum data, follow the steps outlined in the section titled "Restoring a Single-Node Cluster When the Cluster Service Fails."

2. After the system state restore is completed, if Cluster Service starts on the first node, start Cluster Service on all the remaining nodes.

   If Cluster Service does not start, there may be a problem with the cluster quorum drive. Make any necessary repairs on the cluster quorum drive and restore the cluster quorum as outlined in the section "Restoring a Single-Node Cluster When the Cluster Service Fails."

   If Cluster Service still does not start, follow the instructions in the Windows Server 2003 Help and Support article named "Recover from a Corrupted Quorum Log or Quorum Disk."

When all nodes in the cluster are non-operational and the cluster nodes need to be rebuilt from scratch, follow these steps:

1. Power off all nodes in the cluster.

2. Power on only the cluster node and perform an ASR restore as outlined in the section "Restoring the Failed Node Using the ASR Restore." This restore should restore the node and Cluster Service and basic cluster functionality.

3. Restore any missing local disk data and cluster disk data.

4. Perform ASR and local disk restores on remaining cluster nodes to restore complete cluster functionality.

Upgrading Cluster Nodes

Windows Server 2003 Cluster server is compatible with previous versions of Microsoft Cluster Service and can accommodate node operating system upgrades. Windows NT 4.0 clusters must be taken offline before upgrading to Windows Server 2003 clusters, whereas Windows 2000 clusters can be upgraded to Windows Server 2003 while online, utilizing the rolling upgrade method. Before a rolling upgrade can be performed, each resource in the cluster must be checked to see whether it can be upgraded during a rolling upgrade.

---

Note - Resources that do not allow rolling upgrades are IIS, FTP, DHCP, WINS, SMTP, and NNTP services, just to name a few. For detailed instruction on how to upgrade clusters containing these resources, refer to the Help and Support in the Windows Server 2003 operating system and search for "resource behavior during rolling upgrades" and "last node rolling upgrades."

---

Rolling Upgrades

A rolling upgrade allows a single cluster node to be taken offline for an operating system upgrade while the other nodes in the cluster function on the original OS version. On a standalone server, this is referred to as an inplace upgrade. When the upgraded node is back online with the new operating system, the Cluster server is already installed and configured. Cluster groups running on the other nodes can then be moved to the upgraded node, thus enabling administrators to upgrade the remaining nodes in the cluster.

Before attempting a rolling upgrade, the cluster administrator must research all the applications and resources in the cluster to ensure they can be supported during a rolling upgrade. If such an upgrade is not an option, the cluster nodes can be upgraded using the last node rolling upgrade method.

Last Node Rolling Upgrade

The last node rolling upgrade is a process created to upgrade clusters that contain resources that are unsupported during standard rolling upgrades. In this type of upgrade, the administrator moves all the groups containing resources that are unsupported in a standard rolling upgrade to a single cluster node. Then she upgrades all other nodes in the cluster. After all the other nodes are upgraded, she moves the groups with the unsupported resources to the upgraded nodes. Then the administrator performs an operating system upgrade on the last node and redistributes all the cluster groups as necessary.

This chapter is from Microsoft Windows Server 2003 Unleashed, by Rand Morimoto, et al. (Sams Publishing, 2004, ISBN: 0672326671). Check it out at your favorite bookstore today. Buy this book now.

Next: Installing Network Load Balancing Clusters >>
 

More MS SQL Server Articles
More By Sams Publishing

Comments On: System-Level Fault Tolerance (Clustering/Network Load Balancing)

>>> Be the FIRST to comment on this article!