HP Serviceguard Metrocluster with EMC SRDF for Linux B.01.00.00

NOTE: If external_pre_script is specified in a Metrocluster package configuration,
the external_pre_script is executed after the execution of Metrocluster module scripts
in package startup. Metrocluster module scripts are always executed first during package
startup.
5. Run the package on a node in the Serviceguard cluster.
# cmrunpkg -n <node_name> <package_name>
6. Enable global switching for the package.
# cmmodpkg -e <package_name>
After the package is created, if you want to change the value of any Metrocluster parameter, then
edit this package configuration file and re-apply the configuration.
Some further points
Following are some of the requirements specific to EMC Symmetrix:
• Transmit idle mode is not supported. See EMC Solutions Enabler manual to disable it.
• If Linux Native Multipathing is used, all the gate keeper devices have to be blacklisted. For
more information, see EMC Host Connectivity Guide for Linux available at https://
support.emc.com/.
• It is always advised to set Auto_link_recovery for the rdf groups so that if the link comes back,
replication begins automatically.
• R1 and R2 devices must be correctly defined and assigned to the appropriate nodes in the
internal configurations that is downloaded by EMC support staff.
• R1 devices are locally protected (RAID 1 or RAID S); R2 devices are locally protected (RAID
1, RAID S or BCV).
NOTE: HP recommends that the R2 device is locally protected with RAID 1 or RAID S. If
the R2 device is protected with BCV, and if it fails, and there is a failover, then the package
cannot operate on the BCV device. In such a situation, the R2 device must be fixed, and the
data must be restored from the BCV device to the new R2 device before the package can
start.
• Only synchronous and asynchronous modes are supported; adaptive copy must be disabled.
• The Domino Mode must be enabled for M x N configuration to ensure the following:
data currency on all Symmetrix frames.◦
◦ no possibility of inconsistent data at the R2 side in case of SRDF links failure.
If Domino Mode is not enabled and all SRDF links fail, the new data is not replicated to the
R2 side while the application continues to modify the data on the R1 side. This results in the
R2 side containing a copy of the data only up to the point of the SRDF link failure. If additional
failure occurs, such as a system failure, before the SRDF link is fixed, the application fails over
to the R2 side with non-current data.
If Domino Mode is not enabled, in the case of a rolling disaster, the data may be inconsistent.
Additional failures may take place before the system has completely recovered from a previous
failure. Inconsistent and therefore unusable data will result from the following sequence of
circumstances:
◦ Domino Mode is not enabled.
◦ the SRDF links fail.
26 Configuring an application in a Metrocluster solution