Symantec HP-UX manual High availability issues, Network partition/jeopardy

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Storage Foundation Cluster File System problems

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High availability issues

Network partition/jeopardy

Network partition (or split brain) is a condition where a network failure can be misinterpreted as a failure of one or more nodes in a cluster. If one system in the cluster incorrectly assumes that another system failed, it may restart applications already running on the other system, thereby corrupting data. CFS tries to prevent this by having redundant heartbeat links.

At least one link must be active to maintain the integrity of the cluster. If all the links go down, after the last network link is broken, the node can no longer communicate with other nodes in the cluster. Thus the cluster is in one of two possible states. Either the last network link is broken (called a network partition condition), or the last network link is okay, but the node crashed, in which case it is not a network partition problem. It is not possible to identify whether it is the first or second state, so a kernel message is issued to indicate that a network partition may exist and there is a possibility of data corruption.

Jeopardy is a condition where a node in the cluster has a problem connecting to other nodes. In this situation, the link or disk heartbeat may be down, so a jeopardy warning may be displayed. Specifically, this message appears when a node has only one remaining link to the cluster and that link is a network link. This is considered a critical event because the node may lose its only remaining connection to the network.

Caution: Do not remove the communication links while shared storage is still connected.

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Contents HP-UX Sfcfs Technical support Licensing and registrationPage Contents Adding a node to a cluster Chapter Upgrading the productInstalling and configuring the product Hardware overview Cluster platforms Fibre channel switchShared storage Software components Packages installed with Sfcfs onlyPackage Contents Optional packages for Sfcfs and Sfcfs HA Packages ContentsPHKL32272 Required HP-UX patchesPHKL32430 HP-UX Patch ID DescriptionProduct licensing PreinstallationRelease Notes Secure communication Setting Path and Manpath environment variablesPrerequisites Veritas Enterprise AdministratorRequirements Alternatively, remove the file /sbin/init.d/vmsa-serverInstalling the product Enter one or more system names to install Sfcfs If you want to use rsh you must specify on the command lineEnter 1, 2 or 3 to be installed on all systems Change directory to /dvdromConfiguring the Components Do you want to add another user to the cluster? y,n,q y Installation log file Using the log filesResponse file Summary fileLow Latency Transport configuration files Verifying the configuration filesEtc/llthosts Etc/llttabLog into system02 Checking Low Latency Transport operationOutput resembles # lltstat -p Etc/gabtab Group Membership and Atomic Broadcast configuration filesChecking Group Membership and Atomic Broadcast operation Enter the following command on any systems Output for an Sfcfs HA installation resemblesChecking cluster operation See the hastatus1M manualVerifying the configuration files #System Attribute Value Synchronizing time on Cluster File Systems Verifying agent configurationConfiguring VCS Main.cf file Typical VCS configuration file for Sfcfs file resemblesSfcfs HA Only VCS application failover servicesVCS application failover services Upgrading the product Planning the upgrade Preparing to upgrade the productUpgrade paths Complete the following tasks in advance of upgradingMP1 Full upgrade Upgrade OverviewPhased upgrade Change to the top-level directory on the disc Upgrading from 3.5 to# hastart Replace it with Remove VRTSwebRun through , , , and on rest of the nodes to be upgraded See the Veritas Cluster Server Installation Guide Run the following command on all the nodes to start VCS Upgrading from 4.1 to Install all the prerequisite patches and reboot the machines Etc/VRTSvcs/conf/config/main.cf file Full upgrade Etc/VRTSvcs/conf/config/main.cf file Upgrading the disk layout versions # umount /mnt1 Upgrading the disk layout versions Adding and removing a node Enter the system name of the new node to install Sfcfs Enter y to install Sfcfs on these systemsAdding a node to a cluster Change to the Sfcfs directoryStart VxVM on the system that has been added Enter 1 or 2 to be installed on all systemsRun the following command Configuring Sfcfs and CVM agents on the new nodeOpen the VCS configuration for writing Write the new VCS configuration to diskCreate a /mnt on system03 and run the following commands Add shared disk groups to the cluster configurationRemoving a node from a cluster Put the CVM resources back online, in the following order# rm /etc/vxfentab # rm /etc/vxfendg # ./uninstallsfcfs Removing a node from a cluster Enter y to uninstall Sfcfs Enter the system names to uninstall SfcfsUninstalling the product Incorrect permissions for root on remote system Installation issuesResource temporarily unavailable Storage Foundation Cluster File System problemsInaccessible system Mount failures Unmount failuresPerformance issues Command failuresIf this error message displays Following error message displaysNetwork partition/jeopardy High availability issuesLow memory

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