We are using Cassandra 0.8.0 with 8 node ring and only one CF. Every column has TTL of 86400 (24 hours). we also set 'GC grace second' to 43200 (12 hours). We have to store massive amount of data for one day now and eventually for five days if we get more disk space. Even for one day, we do run out disk space in a busy day.
We run nodetool compact command at night or as necessary then we run GC from jconsole. We observed that GC did remove files but not necessarily oldest ones. Data files from more than 36 hours ago and quite often three days ago are still there. Does this behavior expected or we need adjust some other parameters? Yuki Watanabe