Thanks, I've put (for my 16GB RAM / 64 bit machine) into /etc/sysctl.conf: kernel.shmmax = 5000000000 And into postgresql.conf: shared_buffers = 4096MB I didn't change shmall from the default - # sysctl -A|grep shm kernel.shmmax = 5000000000 kernel.shmall = 2097152 kernel.shmmni = 4096 because # getconf PAGE_SIZE 4096 and 2097152 * 4096 < 5000000000, correct? Now PostgreSQL 8.4.x seems to run ok Regards Alex