[Veritas-ha] LLT heartbeat redundancy

[Sandeep Agarwal (MTV)]

Yes, the jeopardy detection etc has not changed.
 
We've just added support for this new type of topology in which the
various LLT links are interconnected (crosslinks).

	-----Original Message-----
	From: John Cronin [mailto:jsc3iii at gmail.com] 
	Sent: Friday, May 08, 2009 6:58 AM
	To: Sandeep Agarwal (MTV)
	Cc: Jim Senicka; Imri Zvik; veritas-ha at mailman.eng.auburn.edu
	Subject: Re: [Veritas-ha] LLT heartbeat redundancy
	
	
	This was certainly news to me.
	
	In this full-mesh heartbeat network, do we still go into
jeopardy if the network links are lost relatively slowly (e.g. if one
link on a node is down for more than 16 seconds by default)?
	
	
	On Sun, May 3, 2009 at 1:07 PM, Sandeep Agarwal (MTV)
<sandeep_agarwal2 at symantec.com> wrote:
	

		From 5.0MP3 onwards we do support cross-links. In your
example if you
		had a cable connecting sw1 and sw2 then the failure that
you described
		would be handled and LLT would still have 1 valid link
between node 1
		and node 4.
		

		-----Original Message-----
		From: veritas-ha-bounces at mailman.eng.auburn.edu
		
		[mailto:veritas-ha-bounces at mailman.eng.auburn.edu] On
Behalf Of Jim
		Senicka
		Sent: Sunday, May 03, 2009 9:23 AM
		To: Imri Zvik
		Cc: veritas-ha at mailman.eng.auburn.edu
		Subject: Re: [Veritas-ha] LLT heartbeat redundancy
		
		LLT is designed to use "jeopardy" to detect the
difference between
		single link fail and dual link fail in most situations.
Having a single
		mesh may remove this capability.
		
		Let me check on this with engineering and see if we have
any more up to
		date recommendations
		
		
		-----Original Message-----
		From: veritas-ha-bounces at mailman.eng.auburn.edu
		[mailto:veritas-ha-bounces at mailman.eng.auburn.edu] On
Behalf Of Imri
		Zvik
		Sent: Sunday, May 03, 2009 12:18 PM
		To: Jim Senicka
		Cc: veritas-ha at mailman.eng.auburn.edu
		Subject: Re: [Veritas-ha] LLT heartbeat redundancy
		
		On Sunday 03 May 2009 19:03:16 Jim Senicka wrote:
		> This is not a limitation, as you had two independent
failures. Bonding
		
		> would remove the ability to discriminate between a
link and a node
		> failure.
		
		I didn't understand this one - With bonding I can
maintain full mesh
		topology - No matter which one of the links fails, if a
node still has
		at least one active link, LLT will still be able to see
all the other
		nodes.
		This achieves greater HA than without the bonding.
		
		
		> My feeling is in the scenario you describe, VCS is
operating properly,
		
		> and it is not a limitation.
		
		Of course it is operating properly - that's how it was
designed to work
		:)
		I'm just saying that the cluster could be more redundant
if it wasn't
		designed that way :)
		
		> If you have issues with port or cable failures, add a
low pri
		connection
		> on a third network.
		
		
		
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