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October 6th, 2009 13:00
Red Hat Cluster Suite cluster.conf settings when using PowerPath
We're setting up a Red Hat Cluster Suite 5 cluster in house here on DMX-3 storage. The quorum device has two paths to its disk. We're using PowerPath 5.3 for the Multipathing and need to know if EMC has recommended values for the following Red Hat Cluster Suite parameters.
All of these settings are in the /etc/cluster/cluster.conf file.
The interval and tko attributes from the quorumd tag:
The cman failover time, specified in the totem token tag:
The quorum_dev_poll tag:
Does anyone know how we should come up with the proper values of these settings on our system? We¿ll need to tell customers how to do this, so it¿d be nice to fully understand the proper method of coming up with these values. Red Hat provides a little guidance, but hinges it on understanding the maximum time that can elapse before a path fails over in PowerPath. How do you determine that maximum time? Is there a PowerPath command that will show you the current setting of that value?
All of these settings are in the /etc/cluster/cluster.conf file.
The interval and tko attributes from the quorumd tag:
The cman failover time, specified in the totem token tag:
The quorum_dev_poll tag:
Does anyone know how we should come up with the proper values of these settings on our system? We¿ll need to tell customers how to do this, so it¿d be nice to fully understand the proper method of coming up with these values. Red Hat provides a little guidance, but hinges it on understanding the maximum time that can elapse before a path fails over in PowerPath. How do you determine that maximum time? Is there a PowerPath command that will show you the current setting of that value?
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Conor
341 Posts
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October 7th, 2009 00:00
RE: The maximum time that can elapse before a path fails over in PowerPath. How do you determine that maximum time?
This value is based on the HBA driver parameters relating to failover times. The HBA driver will retry a failed IO until this timeout expires, if the IO has still not completed, then PowerPath will report the path as dead and re-route the IO to another path.
check out the Emulex and QLogic websites to get the driver manuals for your particular HBA driver, all recommended parameter values are contained within.
Conor
SKT2
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October 8th, 2009 03:00
I would recommend a label for the quorum device rather than specifying the device file. Here is an example from a two node cluster.
the other thing u need to give attention is /etc/modprobe.conf(if Qlogic cards) and make sure fial over is disabled from HBA level rather let PP/array takes care of that.
options qla2xxx ConfigRequired=0 ql2xfailover=0.
As mentioned there is no such recommenations from EMC