thanks for your quickly post.
The systems are running with 4gb memory and 2gb of swap partition.
Swap seems not to be needed, because memory usage at most time is under 50% inluded cache mem.
total used free shared buffers cached
Mem: 3825 1907 1918 0 248 1532
-/+ buffers/cache: 126 3699
Swap: 2055 0 2055
There is not more load ore some special activitiy which induces the problem.
I only can resolve it by rebooting for some hours, is never go away by itself.
But thanks fÃ¼r you advice by purging the cache …it works !!! But what does that mean for me??
I use Kernel 3.0.93-0.8-default and updated yesterday 1 machine to 3.0.101-0.8-default, but the problem still exists with this kernel version.
Of course we have active support subscriptions, but first i would have a look if this is a known bug in the community and hope to be able to fix it myself.