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What is the maximum distance limit of LLT heartbeats

Zahid_Haseeb
Level 6
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ENVIRONMENT

OS = RHEL 7.x

SFHA = 7.x

HA NDOES = 2

QUERY 

What is the maximum lenght/distance limit of LLT heartbeat.

1 ACCEPTED SOLUTION

Accepted Solutions

RiaanBadenhorst
Moderator
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hi,

It's not limited by distance its limited by time. From what I recall, the roundtrip should be less than 500ms.

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3 REPLIES 3

RiaanBadenhorst
Moderator
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hi,

It's not limited by distance its limited by time. From what I recall, the roundtrip should be less than 500ms.

View solution in original post

Zahid_Haseeb
Level 6
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hmm. Suppose in case second node is 100 KMs away with less than 500ms on LLT heartbeats, we can implement local HA.

But a Heartbeat network disconnection can be a concern. How can we cater this to avoid split brain scenario ? any suggestion.

Mouse
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You also need to consider what is the design of your cluster especially the storage, it's unlikely that you can build a reasonably performing shared storage with 500ms RTT, hence you may have a replicated or shared-nothing cluster, the former usually built to tolerate longer RTOs so not a problem and the latter is redundant and usually comes with a load balancing mechanism that solves the problem.

The standard solutions for split-brain arbitration are CPS and SCSI-3 PGR fencing, the latter guarantees both data integrity and membership arbitration, with CPS you may have issues with data integrity on shared storage but again, I doubt that a storage that runs on 500ms RTT can deliver satisfactory performance.