failover issue between datacenters with GSLB

Question

Ok I have been looking for the best solution for an application requirement.

I have an app that will be living in two datacenters. Each location has 4 servers running. What they want is the application to run 100% of the time in DC1 unless 2 or more servers fail in DC1 and then failover to DC2

I thought this would be rather easy, but I have been unable to find a way to get the VIP to go into a down state if two servers have gone down.

Does anyone have a idea how I could implement this?

Thanks

injeyan_kostas · Answer

Hello Brandon_TN​&nbsp;You could use an External Monitor with a custom script to achieve you goalcheck this https://my.f5.com/manage/s/article/K71282813You could then create a dummy Virtual server with a dummy pool and assign the external monitor to itAnd finally use this dummy VS as Dependency for you actual VS in GSLB

injeyan_kostas · Answer

here is an example&nbsp;#!/bin/bash
POOL="Your_Pool_name"
THRESHOLD=2

UP_COUNT=$(tmsh show ltm pool $POOL members | grep "Available Members" | awk '{print $4}')

echo "[$(date)] Pool $POOL has $UP_COUNT members up" &gt;&gt; /var/log/pool_monitor.log

if [ "$UP_COUNT" -lt "$THRESHOLD" ]; then
    echo "[$(date)] Pool DOWN: Only $UP_COUNT members up" &gt;&gt; /var/log/pool_monitor.log
    exit 1
else
    echo "[$(date)] Pool UP: $UP_COUNT members up" &gt;&gt; /var/log/pool_monitor.log
    echo "Pool is healthy" 
    exit 0
fi&nbsp;

vishnugatla · Answer

Update GSLB pool configuration with Minimum Active Members to 3. This means the VIP will be marked down if fewer than 3 servers are up (i.e., if 2 or more fail) .&nbsp;The BIG-IP DNS monitors the VIP. If the VIP is down, GTM will failover to DC2.

injeyan_kostas · Answer

Hi VishnuGatla​ is there such an option?I couldn't find it.

vishnugatla · Answer

Yes, we have that option under GSLB pool config.&nbsp;If we are doing in LTM, K11428303: Priority group assigned to pool members does not take effect&nbsp;

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failover issue between datacenters with GSLB

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