In-Service Migration from iSeries to rSeries Using a Mixed-Platform HA Pair

Hello everyone,

We are planning to migrate an existing pair of iSeries appliances running in an Active-Standby configuration to a new pair of rSeries appliances. The migration will be performed while the service is in production, with the goal of minimizing service interruption.

Until recently, we understood that F5 HA configurations required both devices to use the same hardware platform/model. However, while reviewing the relevant F5 documentation, we came across K8665, which indicates that HA can be configured between devices running on different hardware platforms.

https://my.f5.com/manage/s/article/K8665

I would appreciate your advice and experience regarding the following questions.

1. Are HA Capacity and HA Load Factor required for a two-device Active-Standby pair?

All of our current production iSeries HA configurations consist of two devices in a Sync-Failover Device Group: one Active and one Standby.

K8665 explains that BIG-IP supports redundant configurations between different hardware platforms and also discusses HA Capacity and HA Load Factor in relation to load-aware failover.

In this temporary heterogeneous two-device Active-Standby configuration, do we need to configure HA Capacity and HA Load Factor simply because the two HA members are running on different hardware platforms?

My understanding is that HA Capacity and HA Load Factor are not required simply to establish HA between different hardware platforms. Rather, they are used for load-aware failover, where BIG-IP evaluates the relative capacity of devices and the load of traffic groups when determining the most appropriate failover target.

Since our temporary migration HA pair will contain only two devices, there will be only one possible failover peer:

iSeries (Active) --> rSeries (Standby)

Therefore, I assume that HA Capacity and HA Load Factor are not required for this migration scenario, even though the HA pair consists of different hardware platforms.

Is my understanding correct?

2. Has anyone performed an iSeries-to-rSeries migration using a temporary mixed-platform HA pair?

We are considering the following migration procedure:

1) Restore the UCS configuration from the existing two iSeries devices to the two new rSeries devices, taking the required platform-specific configuration differences into account.

2) Remove the existing iSeries-2 (Standby) device.

3) On the existing iSeries-1 (Active) device, remove the old peer from the Sync-Failover Device Group and Device Trust.

4) Connect the new rSeries-2 device to the L3 switch while keeping it Forced Offline.

5) Re-establish Device Trust and the Sync-Failover Device Group between:

* iSeries-1 (Active)

* rSeries-2 (Standby)

6) Release Forced Offline on rSeries-2 and verify ConfigSync, failover communication, VLANs, Self IPs, pools, virtual servers, and overall service status.

7) Perform an HA failover from iSeries-1 --> rSeries-2.

8) After confirming that services are operating normally on rSeries-2, replace the remaining iSeries-1 device using the same approach.

9) Finally, establish the normal HA pair between the two rSeries devices.

Has anyone successfully performed an iSeries-to-rSeries migration using this type of temporary mixed-platform HA configuration?

3. Are there any feature limitations with mixed-platform HA other than Connection Mirroring?

I understand that Connection Mirroring may have hardware-platform-related limitations when the HA peers are running on different platforms.

Other than Connection Mirroring, are there any known features or functions that are unsupported or restricted when temporarily running an iSeries and rSeries BIG-IP tenant as an Active-Standby HA pair?

We have already confirmed in a test environment that HA can be successfully established between an i2800 and an r2600 BIG-IP tenant, but we would like to understand the official support considerations and any operational caveats before applying this migration method to production.

Any experience, recommendations, or relevant F5 documentation would be greatly appreciated.

Thank you.