Running Systems

It’s sort of a relationship between myself and this Tyan. Same server, changing demands. This time, we’ve had to install on this server RHEL4 32bit.

Net-installing RHEL4 Update 3 was impossible. See here, so we’ve installed it from CDs (didn’t have PCI-X network card handy).

When booting the server, it showed us only a single CPU. Since this machine has four dual-core CPUs, this number – one – was rather unexpected.

We’ve tried booting the system with additional parameters. We’ve tried, per RH tips, to allow “apic=bigsmp” parameter, however, when booting the server with these parameters, the server entered into reset loop. We’ve tried playing with other parameters, such as “apic acpi=noirq iommu=memaper=3 swiotlb=65536” (obtained for Google cache for a forum site which I cannot find again now), but for no avail. Finally, we’ve decided to upgrade the kernel to the one in Update4.

Doing so had special effects. When using it without any special parameters, the server entered a reboot loop, however, when we’ve added the parameter “apic=bigsmp” the server booted correcly and showed all eight CPUs.

This board is a tricky board. 4GB RAM and above behave in a weird manner in Linux. It appears that PCI 32bit mapping doesn’t work correctly under Linux.

To allow Linux to work on this hardware without failure (such as kernel crush during startup), you must follow these three simple guidelines:

1. Spread the memory equally near all CPUs. For example, if you have 4GB RAM for the four CPU version (8 cores, in my case), spread the memory 1GB near each CPU.

2. Make sure you set the type of OS to Linux in the BIOS. PCI mapping won’t work otherwise.

3. Do not put PCI 32bit cards in the PCI-X slots. It will render the onboard network cards unusable.