many thanks for your answer. i have set the option -vv for the memcached but there are no error entrys in the logfile. this is the last logentry:

<7 connection closed. <7 new client connection <7 get website:page:/de/database/1

<7 connection closed.

last night i read some interesting articles. when i run the

netstat -ntc

command, i get hundreds of TIME_WAIT entrys. so i changed the /etc/sysctl.conf file. i changed the following entry from

net.ipv4.ip_local_port_range = 32768 61000

to

net.ipv4.ip_local_port_range = 1024 65000

now my benchmark test works fine. are there any other problems when i run debian with this large port range?