IBM i / AS400 / iSeries / System i Users
What Is Cloud400 High Availability (HA)?
HA generally means you replicate any changes on your production server to a backup, or target server, so you can move your users from your production server to a backup system in a matter of minutes when you have downtime.
How Does Cloud400 HA Work?
For IBM i Logical Replication HA users, your backup server is continuously updated in real-time with Cloud400 HA replication software. Every time your production data changes, the replication software transmits a duplicate copy of the changed object to your Cloud400 backup, or target, server to maintain an identical version of your system.
Logical Replication software executes in the production server main memory and updates are applied by the target server main memory to its database in disk storage.
It is only fair to let you know that there can be latency, or a delay, for your target system to stay current with your production server. The latency results from factors including the replication software design and implementation, your file sizes, your workload volumes and transmission speed. Even so, the latency is significantly faster and your backup copy dramatically more current than a backup tape that can be up to 24 hours old. In most cases, the replication delay can be measured in seconds at most.
With Cloud400 HA, you can move your users from your production server to your target server in a matter of minutes – generally 7 to 15 minutes depending on your user count, your active workload and your network design.
Once your production server is up, you replicate your changed target data to your production server. When your production server is current, you move your users back from the target.
Why Is Cloud400 HA Better?
Cloud400 HA is better for several reasons.
First, when you buy a target server you configure it with peak load disaster recovery capacity. Said differently, you buy more capacity than you need for simple replication.
In contrast, with Cloud400 HA we allocate only as much resource as needed to run HA replication. Since Cloud400 HA is updating a duplicate copy and not performing productive work, you only need a fraction of the processor and memory of a typical physical target server. Because you use less resource than a physical target server, your cost is less.
Also, because you share a portion of a Cloud400 server, the related IBM hardware and software fees are negligible compared to the cost of a physical target server.
Second, when you set up HA between physical production and target servers, you license 2 copies of HA software – one copy for each server. With Cloud400 HA, however, you only license 1 copy of HA software – the copy you need for your production server. In short, your Cloud400 HA software licensing costs and related annual support is about half.
Third, what our Cloud400 HA clients really like is that our data center is supported by OS400 experts 24/7. In most HA set ups we see, the target server is hosted at a branch location or a data center that has limited-to-no OS400 support. Our Cloud400 clients really like that experts are always at hand during downtime to help with user role swap to the Cloud400 target server and back. When the unexpected strikes, it makes a big difference to have experts on hand.