Hi!

I need to replicate an Informix SE 7.25 database in real-time or near-real-time, primarily for failover purposes. I realize there are numerous ways to achieve this, but switching to OnLine isn't among my options.

Has anyone done this? Recommendations? Pitfalls to avoid?

TIA!

Best way is of course upgrade to an IDS where you could implement HDR (High Availability Data Replication).
SE is a low maintenance database. I think you should find a solution on hardware level. You could always implement triggers, but that would impact your production env. preformance.