low water mark ends up > max_size

If you add a bucket and then max_size gets reduced because you added a node or whatever, the high and low water marks don't seem to change, with the result that we never free written data from RAM. It appears that there's no random freeing yet?

Here are stats with about 20k sets per second getting "out of memory" errors.

ep_dbname: c:/Program Files (x86)/NorthScale/Server/data/ns_1/default
ep_total_cache_size: 1321666825
rejected_conns: 0
ep_queue_age_cap: 900
ep_commit_time: 0
ep_oom_errors: 21890424
ep_num_value_ejects: 1146709
ep_bg_min_load: 15 ms
cas_hits: 0
curr_connections: 30
ep_warmup_thread: complete
auth_cmds: 132
ep_max_data_size: 947912704
ep_io_num_read: 940392
ep_min_data_age: 0
ep_bg_wait_avg: 228964270 s
tap_mutation_received: 23887
auth_errors: 0
bytes_written: 3303706909
ep_pending_ops: 0
pointer_size: 32
ep_dbinit: 10
tap_mutation_sent: 48969
ep_io_read_bytes: 1023894140
mem_used: 1072700420
ep_bg_load_avg: 69121289 s
ep_pending_ops_max: 0
ep_bg_max_wait: 18446744073 s
version: 1.4.4_252_g4c4b211
limit_maxbytes: 67108864
ep_version: 1.6.0beta3a_17_g42dc800
bytes_read: 24981572533
ep_mem_high_wat: 1281097728
ep_io_write_bytes: 264413290
daemon_connections: 10
cmd_get: 2183236
ep_num_non_resident: 1140057
ep_bg_fetched: 27640
threads: 4
curr_items: 1130296
conn_yields: 44
get_misses: 0
ep_queue_size: 0
delete_misses: 0
ep_pending_ops_total: 0
cmd_flush: 0
connection_structures: 39
ep_overhead: 12780068
ep_max_txn_size: 50000
ep_item_commit_failed: 0
ep_too_young: 0
total_connections: 181
ep_bg_num_samples: 4270
ep_kv_size: 1059920352
ep_data_age: 44
ep_bg_max_load: 18446744069 s
cas_misses: 0
ep_flusher_state: running
incr_misses: 0
ep_pending_ops_max_duration: 0 usec
ep_total_persisted: 242581
ep_storage_age_highwat: 54
ep_io_num_write: 243752
cmd_set: 22109120
libevent: 1.4.13-stable
ep_item_flush_failed: 0
ep_mem_low_wat: 1024878182
cas_badval: 0
ep_flusher_todo: 0
tap_vbucket_set_received: 42
decr_misses: 0
ep_warmup_time: 10
ep_storage_type: featured
pid: 3968
tap_vbucket_set_sent: 146
ep_warmed_up: 911728
ep_warmup: true
uptime: 2301
bucket_conns: 19
ep_flush_duration_highwat: 56
decr_hits: 0
incr_hits: 0
ep_storage_age: 0
ep_bg_min_wait: 15 ms
ep_data_age_highwat: 55
get_hits: 2183236
ep_flush_duration: 0
ep_too_old: 0
ep_tap_keepalive: 0
tap_connect_received: 92
time: 1282353334
ep_total_enqueued: 243752
delete_hits: 0