[jira] [Created] (CASSANDRA-5552) Cassandra doesn't preload key caches from disk on start

["Alexey Plotnik (JIRA)" <ji...@apache.org>]

Alexey Plotnik created CASSANDRA-5552:
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             Summary: Cassandra doesn't preload key caches from disk on start
                 Key: CASSANDRA-5552
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-5552
             Project: Cassandra
          Issue Type: Bug
          Components: Core
    Affects Versions: 1.1.9
         Environment: CentOS 6.2, Datastax Cassandra Commutnity Edition package
            Reporter: Alexey Plotnik


My cache related settings is default :
  key_cache_size_in_mb: # no value here
  key_cache_save_period: 14400
  row_cache_size_in_mb: 0
  row_cache_save_period: 0
  row_cache_provider: SerializingCacheProvider
  saved_caches_directory: /var/opt/cassandra/data/saved_caches

Every time I restart Cassandra with `service cassandra stop; service cassandra start` I see with Zabbix or JMX or `nodetool info` the key cache was nulled. It happens every time I restart the node. This situation is on all the nodes I have. I guessed since key cache is flushed to disk every 4 hours I should never see the situation with cold caches.

nodetool info output after 30 minutes from node has been started:
Key Cache        : size 2105664 (bytes), capacity 104857584 (bytes), 3812 hits, 47610 requests, 0.371 recent hit rate, 14400 save period in seconds

Before restarting it looked as follows:
Key Cache        : size 104857584 (bytes), capacity 104857584 (bytes), 79777150 hits, 502884072 requests, 0.847 recent hit rate, 14400 save period in seconds

All the nodes have cache capacity auto-calculated to 104857584 (100 Mb)

The capacity of saved_caches directory on all the nodes is strange: with `ansible cassandra -i hosts -m raw -a 'du -s /var/opt/cassandra/data/saved_caches' | grep caches` I see values from 50-100 Kb only against values of 100Mb the `nodetool info` outputs.

After node has been restarted in 1 week key cache is filled up to ~2,2 million of keys, but when I perform node restart (after > 4 hours of running) it nulled again.

I've never changed the default configuration of cassandra caches.

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