Maximum distance between HA devices / sync
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Hi,
I have deployed several HA/CARP/VIP instances in the past in data cabinets, however I would like to deploy in a small hospital setting and I was wondering if there was a maximum distance between the HA nodes.
Scenario: West side of the building MPOE, INcoming WAN (cable), Central/East side of the building MPOE another INcoming WAN from a different provider (microwave).
We have fiber runs from East to West and to Central terminating on patch panels and FO panels.
I would like to deploy one HA member in West MPOE with one WAN circuit, and deploy the other HA member in the East side server room with the other WAN circuit, tie them together with the fiber runs from East to West. ie. x2 WANs and x1 Sync and at least x2 LAN's, one for each side. If East goes down, West can take over.
I plan to set a switch in front of each WAN to split out the circuit to each node.
Is there a limitation with the distance between East and West? Maybe half a city block max between East and West.
Thanks!
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As long as the L1/L2 between them is clean and fast that should be OK. You can adjust advbase if it isn't. With a higher advbase it won't fail over as fast, but it is more tolerate of latency between the nodes. Having them in different places in the same building is not unheard of, or even separate buildings on the same campus. It's not ideal but it can work. I think we even had someone try to use CARP for HA to a node in a DC as some attempt at DR, but I can't remember if that ended up working in the end.
When working with skew and base values for CARP VIPs, Skew values are 1/256th of a second, and base values add whole seconds. So if you set advbase to 1, then it would wait 1 second + skew, rather than only the skew time.
