Issue

Performance tuning issue for Sybase ASE running on RHEL 5.5. We see time periods where swapping happens and want to tune certain parameters and need recommendations.

1. Our current build sets vm.pagecache to 0. I do not have histroy on this but according to documentation, this is an interesting feature that was available, then removed, and then put back but with different settings. Documentation does not completely explain.

2. We also set vm.swappiness to 40. Most of the documentation states that it should be set to 10 for databases. There are notes that also state this tunable was more important than setting pagecache.

3.Also if TMPFS is used there is a question about setting swappiness to 0 to keep pages from getting pulled from this filesystem.