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RamDisc volume group recovery following a vgscan command...
Introduction: This document describes a command line procedure that may be required to recover RamDisc volume groups following the execution of the vgscan command. The man page for the vgscan command states This command should be run only in the event of a catastrophic error such as the deletion of the /etc/lvmtab file or the mismatch of names of the physical volumes in the /etc/lvmtab file to the actual physical volume path configuration. This command will re-construct /etc/lvmtab by searching throughout the typical disk I/O of the system and find physical volumes that belong to each volume group. However, the vgscan command is not aware of the RamDisc devices belonging to RamDisc volume groups and does not include them in the newly created /etc/lvmtab file. Based on how your RamDisc is configured, the following describes the process of restoring RamDisc volume groups to the system.
Please contact RamDisc technical support if you have any questions or concerns before attempting any file edits or scripted command listed in the sections below. Upgrade your current RamDisc software to revision 4.03 or greater (your support contract allows an online license upgrade from release 3 to 4 using our website). If a disk device file that is either mirrored to a RamDisc voume group or part of a RamCluster changes in ioscan to another device file (due to changes to the I/O of the system), contact RamDisc technical support before performing the following. Section 1: Working with RamOnly volume groups (no mirroring and no ServiceGuard) Section 2: Working with RamDisc mirrored volume groups (without ServiceGuard) Section 3: Working with RamCluster mirrored volume groups (ServiceGuard packages)
Section 1: Working with RamOnly volume groups (no mirroring and no ServiceGuard) Using RamDisc software revision 4.03 or greater only requires a scheduled reboot of each configured system to restore the RamOnly volume groups. While activated, the volume group(s) will remain online and useable until the next system shutdown.
Section 2: Working with RamDisc mirrored volume groups (without ServiceGuard) Make a backup copy of /etc/rc.config.d/ramvol and place it in /tmp directory. The backup copy must not reside in the /etc/rc.config.d directory. Open the ramvol file (in /etc/rc.config.d dir) for edit. Look at the PVCPRI_DISK variables. There are 9 indexed variables of this type. Note the index numbers of the PVCPRI_DISK variables that contain disk device files. The index number (a number between the left and right bracket) will match the last character of the RamDisc volume group name(s) that are mirrored (/dev/vr0x). You will also notice 9 indexed variables called VGROUP_STAT. For any PVCPRI_DISK variable that has device files defined, change the VGROUP_STAT variable within the same index number from the word Enable to Import (Note the uppercase letter 'I' as this word is case sensitive). Reboot the system after saving changes to the file and the volume group will be restored.
Section 3: Working with RamCluster mirrored volume groups (ServiceGuard packages) Make sure that any packages with a RamCluster configured are halted and will not auto start when the cluster is started. Besides changing the word Standby to the phrase RCport (Note the uppercase letter 'R' and 'C'), follow the instructions in Section 2 on each system the vgscan command was executed, then reboot each system so the cluster is formed but not running any packages containing RamClusters. Log in to each system and change to the /usr/local/etc/ramdisc/sysadmin directory. In this directory you will see files that have a ramcluster_ prefix. For each volume group configured as a RamCluster, run ./ramcluster_postvgscan /dev/vr0x (letter x matches the last character of the volume group name and the index number(s) noted in the ramvol file). If you used vgscan on both systems in the cluster, you will need to run the ramcluster_postvgscan script on the other system as well with the warning that it is very important to wait until the script completes on the initial system first. (Do not execute more than once per volume group or simultaneously.) After the ramcluster_postvgscan script has been run for each RamCluster volume group (as needed on the other system as well), to check functionality, execute ./ramcluster_run (only on 1 system) and check the mounted filesystems. When you are satisfied, execute ./ramcluster_halt and the RamCluster lvols will be offline and the volume group(s) deactivated. Perform the same steps with ramcluster_run and ramcluster_halt on the partner system to insure it works as well. You can now start your packages and configure them for auto run if you desire. An additional test would be to shutdown and reboot both systems if you have spare time to do so.
Please note that the RamDisc automated LVM recovery from a vgscan command as documented above
can only be performed if your current RamDisc software revision is 4.03 or greater.

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