RTMP automatically destroys because of high storage writes.

Is RTMP using disk for any use? How can we minimize disk usage?
We generally use only use 1 stream with 1 client and sometime in between any 10 days It stops working automatically.
here is the config.
rtmp {
server {
listen 1935;
chunk_size 4000;
ping 30s;
ping_timeout 15s;
idle_streams off;
buflen 20s;
drop_idle_publisher 15s;
access_log /dev/stdout;
application livestream {
live on;
interleave on;
record off;
sync 10ms;
}
}
writes approx 0.3 mb per minutes