ptx/CLUSTERS V2.2.1 Release Notes


Introduction

These release notes support ptx®/CLUSTERS V2.2.1. Read this document before you install or run this release of ptx/CLUSTERS.


Product Compatibility

This version of ptx/CLUSTERS can be used with the following products:

For product compatibility information on products such as ptx/LAN and ptx/TCP/IP, consult the DYNIX/ptx and Layered Products Software Installation Release Notes.

If you wish to use Oracle® Parallel Server, we recommend Oracle V7.3.4 or higher.


Supported Cluster Configurations

This release of ptx/CLUSTERS supports the following configurations:

This release of ptx/CLUSTERS does not support ``mixed'' cluster configurations of Symmetry 5000 and NUMA-Q systems. This release also does not support the use of Fibre Channel Arbitrated Loop on NUMA-Q 2000 systems.


Fixed Problems in This Release

This release of ptx/CLUSTERS contains fixes for the following software defects:


Changes in the ptx/CLUSTERS V2.2.0 Release

The following sections describe changes to the ptx/CLUSTERS software that were introduced with the ptx/CLUSTERS V2.2.0 release.


Fixed Software Defects

The ptx/CLUSTERS V2.2.0 release contained fixes for the following software defects:


Automatic Synchronization of Names in the Naming Database

With V2.2.x, ptx/CLUSTERS ensures the names of shared devices are synchronized throughout the cluster; that is, a shared device is guaranteed to have the same name on all cluster nodes. If devices are added or removed or the name of a device is changed from one cluster node, the changes will be propagated to all the other cluster nodes. Under normal circumstances, if changes are made to device names while some of the cluster nodes are down, the changes will be propagated to these nodes when they rejoin the cluster.


How the Naming Database Has Changed

The naming database is a replicated database; a complete copy of the database is stored on each cluster node. You can make changes to the naming database using the devctl command. In releases prior to ptx/CLUSTERS V2.2.x, the naming database on each node is independent. devctl commands affect only the naming database on the system on which they are run. To keep the naming databases synchronized, the administrator must manually make identical changes to all the naming databases in a cluster.

In ptx/CLUSTERS V2.2.x, the devctl command coordinates with all the cluster members to ensure any changes are made to all the naming databases together. In addition, when a new node joins an existing cluster, its naming database is updated to be the same as the naming databases of the existing members.

To support this new functionality, the format of the naming database in ptx/CLUSTERS V2.2.x differs from earlier releases. The new naming database has version numbers and timestamps which allow a cluster to determine which naming database is the most recent version. Also, the quorum disk, if configured, stores naming database version information. A ptx/CLUSTERS V2.2.x system can read both pre-ptx/CLUSTERS V2.2.x and ptx/CLUSTERS V2.2.x naming database formats. When a ptx/CLUSTERS V2.2.x system boots on a node with an earlier version of the naming database, it will rewrite the database to be in ptx/CLUSTERS V2.2.x format.


How ptx/CLUSTERS V2.2.x Ensures Naming Database Changes Are Made Identically on All Nodes

ptx/CLUSTERS uses a mechanism similar to that of cluster quorum to ensure that naming database copies are identical on all cluster nodes and to ensure that naming database changes are not lost during cluster node failures. Cluster quorum is based on the idea of an expected number of cluster members. The number of members expected starts at 2 (in ptx/CLUSTERS V2.2.x) and is increased whenever additional cluster members arrive. A quorum of members is a strict majority. If a quorum of members participate in a calculation, it is guaranteed there is no other independent set of cluster nodes which also comprise a quorum of members.

For naming databases, the logic is similar. The cluster maintains the number of naming database replicas it expects to participate in the naming database update protocols. If a set of nodes constitute a quorum of naming database replicas, they can use and update the naming database knowing that there are no other groups of cluster nodes doing the same thing and that changes in the naming database will be preserved across failures of the nodes.

A node synchronizes its own naming database with the naming databases of the rest of the cluster members when the rc2.d/S02deactivate script issues a devctl -A command. The command waits until a quorum of naming database replicas is present in the cluster. They then decide which naming database is the newest and all members synchronize their naming databases to that version. Subsequently, any changes made to the naming database from one node are simultaneously made on all the nodes. When a new node joins the cluster which already has a quorum of members, it synchronizes its naming database to the version determined by that quorum.

One important result of the naming database changes is that it is no longer possible to change the naming database by replacing the /etc/system/ndb file. Neither a copy of a naming database from a different machine or a copy of a naming database from the same machine will work correctly if it is simply copied into /etc/system/ndb. The only way the contents of a naming database file may be installed in the active naming database is by using the devctl -l command.


New Utilities for Checking Node Configuration and Naming Database Consistency

This release of ptx/CLUSTERS includes the following two utilities, which are installed in /sbin:

ccvd
The Cluster Configuration Verification and Determination (ccvd) utility may be used to check the configuration of single nodes in a cluster, all nodes in a cluster, or new nodes that are going to be joining the cluster. ccvd checks the configuration of each node and records any errors it encounters in a tar file when logging is turned on.
ndbcomp, ndbcompall
The naming database comparison (ndbcomp) utility compares the naming databases of clustered nodes to ensure that all shared devices are configured the same in each naming database (ndb) specified on the command line. If ndbcomp encounters any errors, a description of the error, the record type, the specific device(s), and other relevant information are displayed to stdout.

Each ndb file that is going to be compared needs to be copied to the local system, or you can use ndbcompall instead. ndbcompall locates all the nodes in the cluster, copies over the ndb files, and gives them to ndbcomp for comparison.

For more information about these utilities, see the ndbcomp and ndbcompall man pages.


Install ptx/CLUSTERS

For instructions on how to update ptx/CLUSTERS, DYNIX/ptx, and other IBM NUMA-Q products running on Symmetry systems, see the DYNIX/ptx and Layered Products Software Installation Release Notes.

IBM NUMA-Q authorizes only IBM NUMA-Q personnel to perform initial cluster installations and to upgrade NUMA-Q 2000 clusters. IBM NUMA-Q Customer Support or Professional Services personnel who install new clusters or update NUMA-Q 2000 clusters should follow the procedures in the ptx/CLUSTERS V2.x Installer's Guide and in the DYNIX/ptx and Layered Products Software Release Notes for installation and configuration.


ptx/SVM Limitations in 3- and 4-Node Clusters

ptx/SVM V2.2.x cannot be used to manage shared storage on clusters containing more than 2 nodes. ptx/SVM can be used for mirroring root and primary swap on local disks on the nodes of 3- and 4-node clusters. See the ptx/SVM V2.2.1 Release Notes for more information about the limitations of ptx/SVM in 3- and 4-node clusters.


Changing Cluster Node ID

Normally, when changing a node ID in a cluster, you need to reboot only the node whose ID you are changing. However, because of a defect in the software (problem report 235185), after changing the ID of one node or more nodes, you need to reboot all nodes.

To change the node ID, follow these steps:

  1. Issue the clustadm -P nodeid=value command, where value is the new node ID (an integer between 0 and 7, inclusive). Issue this command on each node whose ID you wish to change.

  2. Shut down all cluster nodes. The recommended procedure is to first bring all the nodes to run-level 1, and then bring them to the firmware level.

  3. Start the cluster nodes back up.

Failure to follow this procedure can cause the same node to appear multiple times in clustadm output and may cause the Lock Manager to hang.


Using Disks Containing VTOCs with ptx/SVM

In ptx/CLUSTERS V1.x, if you built a VTOC on a shared device from one of the nodes, the disk's slices were then available on all of the cluster nodes. In ptx/CLUSTERS V2.x, the remaining node(s) will not be aware of the existence of the VTOC slices if you build a VTOC on a shared device from only one of the nodes.

If you wish to place a disk containing a VTOC under ptx/SVM control and use the disk in a cluster, then you must assure that each member node's /etc/devtab file contains a VTOC entry for that disk. Then issue the devbuild command to create the virtual devices included in that VTOC on all nodes in the cluster.

If you build the VTOC for a disk on one node (where the disk will be recognized as a ``sliced'' disk), but not on the other node(s) (where the disk will be recognized as a ``simple'' disk), then the ptx/SVM shared disk groups will not match across the cluster and you will not be able to use them.


Forced Node Shutdown of a Cluster Node

There are several situations in which it is necessary for the Integrity Manager to reboot a cluster member node. In these situations, the node has become unable to safely resume access to shared storage. The Integrity Manager invokes the kernel panic mechanism to prevent any further user-level activity that might require access to shared storage and to bring the node most rapidly back into cluster membership. The panic messages used, and their causes, are the following:


Guidelines for Removing a Node from a Cluster

To remove a node from a cluster, follow these steps:

  1. Shut down the node you wish to disconnect from the cluster and power it off.

  2. Disconnect all shared storage from the node to be removed from the cluster.

  3. Disconnect the node from the CCI networks.

  4. Boot the node you wish to remove from the cluster. Go to single-user mode, either with the bootflags or by entering s at the Waiting for cluster membership, enter 's' to go to single-user mode prompt.

  5. Through ptx/ADMIN, deinstall the ptx/CLUSTERS software. For information on how to deinstall software, see the DYNIX/ptx and Layered Products Software Installation Release Notes.


    ATTENTION

    To avoid destroying or corrupting data, do not remove the ptx/CLUSTERS software before detaching the node from all shared storage.


  6. On the remaining nodes, reset the number of expected votes to equal the number of remaining nodes plus the quorum disk, if one is configured.


Product Documentation

The ptx/CLUSTERS V2.2.1 documentation includes the following:


Problem Reports

This section lists open problems in this release of ptx/CLUSTERS. The numbers in parentheses identify the problems in the IBM NUMA-Q problem-tracking system.


Node Index Change Causes IMD to List Same IP Address Twice (235185)

When a node index is changed on one cluster node and the node is restarted, the unchanged node has two entries for the node whose index has changed. One entry is for the original node index, and the other entry is for the new node index.

Workaround. See the section in these release notes entitled "Changing Cluster Node ID" for information on how to change a node's index.


Installation of ptx/CLUSTERS Removes ptx/CTC Menu Entries (237168)

ptx/CTC menus in ptx/ADMIN are removed if an updated version of ptx/CLUSTERS is installed and ptx/CTC is not reinstalled.

Workaround. Always install ptx/CLUSTERS and ptx/CTC together. If you have already installed ptx/CLUSTERS, install ptx/CTC from the CD-ROM so that the menus will reappear.


ptx/CLUSTERS Does Not Recognize CCI Name Changes Done Through devctl (241128)

When you use devctl to change the name of a CCI device, ptx/CLUSTERS does not know the name has changed.

Workaround. Use clustadm to deconfigure and reconfigure the CCI device.


clustadm -C and clustadm -D Hang When Node Has Lost Quorum (241693)

The clustadm -C (configure quorum disk) and clustadm -D (deconfigure quorum disk) will hang when the node has lost quorum. The commands cannot be suspended or interrupted.

Workaround. Boot another node to restore quorum or reboot the node and only make quorum disk configuration changes while the node has quorum.


devdestroy Fails for Device That Hosted the Quorum Disk (243003)

When a quorum disk is configured, the VTOC, if it is not already in place, is built for the device on remote nodes from the kernel. However, this does not update the list of built devices at the user level.

Workaround. Execute the devbuild command on the node where the devdestroy is failing. Doing so will update the list of built devices. Then do the devdestroy.


A Node May Be Down or Powered Off and Other Nodes May Report It Is Still a Cluster Member (246261)

When a cluster member node is shut down, the other member nodes will continue to report that it is a member until VSYNC has completed its membership view change protocol. This protocol includes a delay known as "I/O drain time," during which the view change waits for completion of any I/O requests initiated before the node was shut down to either complete or fail. Thus it is possible, if this I/O drain time is long enough, for a node to be completely shut down and even powered off while clustadm on other nodes continues to report that the node is still a cluster member. clustadm will report that all links to the shut down node are DOWN during this delay in the membership view change protocol. This is the indication that the protocol is underway and should complete shortly.

Workaround. This is a transient problem which will correct itself after the I/O drain time delay has passed.


Conflict Messages Appear when ptx/CLUSTERS Is Deinstalled Through ptx/INSTALL (249704)

Conflict messages for several files appear when ptx/CLUSTERS is deinstalled through ptx/INSTALL. The conflict message for each file is:

/sbin/ptxinstall/remove: File to be deleted does not exist

Workaround. These messages can be safely ignored; the deinstallation will not fail because of them.


ptx/SDI Must Be Installed on All Nodes or No Nodes (250365)

If one cluster node is running ptx/SDI and has a ptx/SDI device, then another node that attempts to join the cluster must also have ptx/SDI installed. Likewise, if an existing cluster node does not have ptx/SDI installed, then another node that attempts to join the cluster must also not have ptx/SDI installed. Otherwise, when the nodes attempt to synchronize their naming databases, the following error will occur:

devctl: Internal error 3 during NDB merge operation: Invalid argument
devctl: unable to synchronize NDB: Invalid argument

Workaround. Ensure that ptx/SDI is either installed on all cluster nodes or on none.


devctl Commands May Not Be Propagated to All Cluster Nodes (251549)

When the devctl command is used to deconfigure or configure devices, the results may not be propagated to all nodes in the cluster if the devctl command is executed just before a cluster membership transition begins.

Workaround. Try not to configure or deconfigure devices when the cluster is transitioning. Use the /sbin/ndbcompall command to verify that the devctl command was propagated to all nodes. If it was not, shut down and reboot the nodes to resynchronize the cluster nodes' naming databases.