Faster Refresh, Less Bandwidth: How *ZLIB Compression Accelerates iCluster Replication
If you're running iCluster in a large IBM i environment, you've probably felt the pain of long refresh windows. A full object refresh in SAVRST format can take hours, consuming network bandwidth and tying up system resources while your team waits.
The bigger your environment gets, the worse it scales. More objects, more data, longer windows — and less room for error when you're trying to keep your replication current.
What's New in iCluster 9.4.1: *ZLIB Compression for SAVRST Refresh
iCluster 9.4.1 now supports *ZLIB as a compression option for SAVRST refresh operations. It's added directly to the existing Object Compression setting in DMSETSVAL, alongside the familiar *NO, *YES, *MEDIUM, and *HIGH options. No new commands to learn, no new configuration workflow — just select *ZLIB and go.
In testing, *ZLIB compression delivers up to 5x faster refresh performance compared to previous compression options.
Hardware Acceleration on Power10
On IBM Power10 systems, *ZLIB can take advantage of the NX GZIP hardware acceleration engine. Instead of burning CPU cycles on compression, the work is offloaded to dedicated hardware — giving you faster compression with lower system overhead.
This is especially valuable for environments running on Power10 where you want to maximize platform investment.
Platform Requirements
- IBM i 7.5, or IBM i 7.4 TR7 with required PTFs
- Power10 NX GZIP acceleration available on supported systems
- Enabled through the existing DMSETSVAL Object Compression setting
The Bottom Line
Shorter refresh windows, less network usage, and better utilization of modern IBM Power hardware. If you're already running iCluster with SAVRST refresh, enabling *ZLIB is a one-setting change that can make a significant difference.
