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Known workarounds with RamDisc and ServiceGuard...
There are a few ServiceGuard commands that will scan all known LVM volume groups configured (even those not included in the cluster) while performing their tasks. The command may result with an error indicating a problem with /dev/vr0X (the 'X' matching a RamDisc volume group) or /dev/dsk/crtXd0 (RamDisc device files). This error occurs when the command attempts to gather physical disk device LVM data on a RamDisc device file. Here is an example of errors from the cmcheckconf command: # cmcheckconf -C ramcluster.ascii Error: Unable to determine a unique identifier for physical volume /dev/dsk/crt8d0 on node cluster1. Use pvcreate to give the disk an identifier. This error will occur while using the cmapplyconf command as well. The workaround is to use the '-k' option during cmcheckconf and cmapplyconf commands. Here is a cut-and-paste from the cmcheckconf man page: the -k option means that cmcheckconf only checks disk connectivity to the LVM volume group that are identified in the ASCII file. Omitting the -k option (the default behavior) means that cmcheckconf tests the connectivity of all LVM volume groups on all the cluster nodes. Using -k can result in significantly faster operation of the command. This option will ignore any RamDisc volume group configured on the system and allow the command to succede simply by adding '-k' before the '-C' option in cmcheckconf & cmapplyconf. The cmgetconf command does not support the '-k' option. There is a program in the /usr/local/etc/ramdisc/sysadmin directory called ramcluster_devices that corrects this error while the cmgetconf command is executing. Incuding a block disk device file that points to the same RAID LUN as an option to the ramcluster_devices will create a temporary redirect for all RamDisc device files allowing the cmgetconf command to succede. The ramcluster_devices script must be executed simultaneously on each cluster node just before executing the cmgetconf command (or just before the ServiceGuard GUI utility performs the command). _________________________________________________________________________________
Known workarounds with RamDisc and Dynamic Root Disks...
Some options of the drd command attempt to scan all LVM volume groups configured group(even the non-Root disk volume groups) while performing their tasks. The drd command may error indicating a problem while "Reading Current System Information". This type of error occurs when the command attempts to gather physical drive info using a RamDisc device file. A simple modification of an ASCII script file called /opt/drd/lbin/drd_save_config will provide the solution to the workaround. Backup the /opt/drd/lbin/drd_save_config file. Change the following two red lines into the blue text within the file: vgdisplay 2>/dev/null | grep "^VG Name" | awk ' { print $3 } ' | vgdisplay 2>/dev/null | grep -v "/dev/vr0" | grep "^VG Name" | awk ' { print $3 } ' | sort -u $whole_disk_temp_file | sort -u $whole_disk_temp_file | grep -v "/dev/dsk/crt" | Save the file and now all DRD commands will ignore RamDisc devices.
Please note that the RamDisc workarounds with ServiceGuard as documented above can only be
performed if your current RamDisc software revision is 4.00 or greater.

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