Clustering

Upgrading or downgrading the Citrix ADC cluster

All the nodes of a Citrix ADC cluster must be running the same software version. Therefore, to upgrade or downgrade the cluster, you must upgrade or downgrade each Citrix ADC appliance of the cluster, one node at a time.

A node that is being upgraded or downgraded is not removed from the cluster. The node remains a part of the cluster and serves traffic uninterrupted, except for the downtime when the node reboots after it is upgraded or downgraded.

However, due to software version mismatch among the cluster nodes, configuration propagation is disabled on the cluster. Configuration propagation is enabled only after all the cluster nodes are of the same version. Since configuration propagation is disabled during upgrading on downgrading a cluster, you cannot perform any configurations through the cluster IP address during this time.

Important

In a cluster setup, a Citrix ADC appliance might crash, when:

  • upgrading the setup from Citrix ADC 13.0 47.x or 13.0 52.x build to a later build, or
  • upgrading the setup to Citrix ADC 13.0 47.x or 13.0 52.x build

Workaround: During the upgrade process, perform the following steps:

  • Disable all cluster nodes and then upgrade each cluster node
  • Enable all cluster nodes after all the nodes are upgraded

Points to note before upgrading or downgrading the cluster

  • You cannot add cluster nodes while upgrading or downgrading the cluster software version.

  • You can perform node-level configurations through the NSIP address of individual nodes. Make sure to perform the same configurations on all the nodes to maintain them in sync.

  • You cannot run the start nstrace command from the cluster IP address when the cluster is being upgraded. However, you can get the trace of individual nodes by performing this operation on individual cluster nodes using their NSIP address.

  • Owing to the changes in cluster licensing that were made in NetScaler 10.5 Build 52.11 see Prerequisites for cluster nodes, look into the following:

    • If the cluster is set up using a build earlier than NetScaler 10.5 Build 52.11, the cluster works with the separate cluster license file. No changes are required.

    • If the cluster is set up in NetScaler 10.5 Build 52.11 or later releases and then downgraded to a build earlier than NetScaler 10.5 Build 52.11, the downgraded cluster does not work as it now expects a separate cluster license file.

  • While upgrading from any NetScaler 10.1 build to a later release, SYN cookie must be disabled on all TCP profiles (using the set ns tcpProfile <name> -synCookie DISABLED command). After that a striped SNIP must be added on the CLIP subnet. Once upgraded, SYN cookie can be enabled again.

  • While upgrading the Citrix ADC appliance from a NetScaler 10.1 build to a NetScaler 10.5 build, do not run the “show audit messages” command as this can cause the Citrix ADC appliance to become unresponsive.

  • NetScaler 10.5 54.x and 55.x builds are not suitable for cluster deployment. This is because, for services that need probing, SYN packets are processed locally (on the flow receiver) even though SYN cookie is disabled.

  • Citrix ADC 13.0 47.x and 13.0 52.x builds are not suitable for cluster deployment. This is because the inter-node communications are not compatible in these builds.

  • When a cluster is being upgraded, it is possible that the upgraded nodes have some additional features activated that are unavailable on the nodes that are not yet upgraded. This results in a license mismatch warning while the cluster is being upgraded. This warning is automatically resolved when all the cluster nodes are upgraded.

Important

  • Citrix recommends that you wait for the previous node to become active before upgrading or downgrading the next node.

  • Citrix recommends that the cluster configuration node must be upgraded/downgraded last to avoid multiple disconnects of cluster IP sessions.

To upgrade or downgrade the software of the cluster nodes

  1. Make sure the cluster is stable and the configurations are synchronized on all the nodes.

  2. Access each node through its NSIP address and perform the following:

    • Upgrade or downgrade the cluster node. For detailed information about upgrading and downgrading the software of an appliance, see Upgrade and downgrade a NetScaler appliance.

    • Save the configurations.

    • Reboot the appliance.

  3. Repeat step 2 for each of the other cluster nodes.

Upgrading or downgrading the Citrix ADC cluster