Recently there has been a small bug fix for the swap behavior of Linux on System z. The following problem has been observed by several users:
The first time Linux started swapping it was doing so really extensively even though only a small amount of additional memory was needed. Depending on the disk speed and size of the swap space this can take a while.
The fix is included in
- RHEL 5.7.z update 2.6.18-274.11.1
- RHEL 6.2 base 2.6.32-220
- SLES 10 SP4 kernel update 188.8.131.52-0.91.1
- SLES 11 SP1 kernel update 184.108.40.206-0.3.1
and will be available for the other distros in the future as well.
As the system becomes totally unresponsive during that period I really
recommend to get this fix installed if your system has more than a
minimal swap attached and you are experiencing heavy first time swapping
now and then. Contact your distribution partner or service provider in this case to get a temp fix.