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Best practices for failover without heartbeat

Created: 24 Oct 2012 | Updated: 24 Oct 2012 | 2 comments
mkruer's picture
mkruer
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I dont think there is a solution to this, becuse it would violate HA, but I need to ask the question.

Prerequisite: HA Setup is up and running.

Steps:
1). Unplug the heartbeat cable. (eth1)
2). Unplug/failover the primary system.

Secondary system does not come up without manually enabling the autodisable on
the faulted primary.

They want the secondary system to come up. Automaticly.

Is this possable? is it recomemned?

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Marianne van den Berg's picture
Marianne van den Berg Trusted Advisor Partner Accredited Certified
Best practices for failover without heartbeat - Comment:24 Oct 2012 : Link

They want the secondary system to come up. Automaticly.

WHY?? 
What if primary is up and running, still having all clustered applications up and running?
Have you ever seen 'split-brain'? Not pretty.
Data corruption that can only be fixed by restoring all data.

Autodisable is a protection mechanism. Understand that it is there to protect your data.

Step 1 suggests that cluster has one heartbeat only. VCS needs two heartbeats.
Please read up in VCS Admin Guide : 
About communications, membership, and data protection in the cluster

See these topics:

 

■ About data protection
■ About I/O fencing configuration files
■ Examples of VCS operation with I/O fencing
■ About cluster membership and data protection without I/O fencing
■ Examples of VCS operation without I/O fencing
■ Summary of best practices for cluster communications

The solution here is to follow the 'best practices for cluster communications', e.g:

 

■ Configure multiple independent communication network links between cluster systems.
Networks should not have a single point of failure, such as a shared switch or
Ethernet card.
■ Low-priority LLT links in clusters with or without I/O fencing is recommended.
In clusters without I/O fencing, this is critical.
...
■ Symantec recommends at least three coordination points to configure I/O
fencing. You can use coordinator disks, CP servers, or a combination of both.
Select the smallest possible LUNs for use as coordinator disks. No more than
three coordinator disks are needed in any configuration.
 
(More in the manual....)

 

Supporting Storage Foundation and VCS on Unix and Windows as well as NetBackup on Unix and Windows
Handy NBU Links

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arangari's picture
arangari Symantec Employee
Best practices for failover without heartbeat - Comment:24 Oct 2012 : Link

does customer have Fencing enabled? 

 

Thanks and Warm Regards,

Amit Rangari

If this post helped you resolving the issue, please mark it as solution. _____________________________________________________________________________

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