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

["Jonathan Ellis (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-5552?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jonathan Ellis resolved CASSANDRA-5552.
---------------------------------------

    Resolution: Duplicate
    
> 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
>              Labels: performance
>
> My cache related settings is default:
> {quote}
> 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
> {quote}
> Every time I restart Cassandra node with *service cassandra stop; service cassandra start* commands I see with Zabbix or JMX or *nodetool info* the key cache has been nulled. It happens every time I restart the node. This situation is stable on all the nodes of the cluster. I guessed since the key cache is flushed to disk every 4 hours I should never see the situation with cold caches.
> The output of *nodetool info* after 30 minutes from node has been started:
> bq.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:
> bq.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 the cache capacity auto-calculated to 104857584 (100 Mb) according to settings I put above.
> The capacity of saved_caches directory on all the nodes is strange: with command
> bq.ansible cassandra -i hosts -m raw -a 'du -s /var/opt/cassandra/data/saved_caches' | grep caches
> I see values from 50 to 100 Kb only, against the values of 100Mb the `nodetool info` outputs.
> After node restart in 1 week the key cache is filled up to ~2,2 million of keys, but when I perform node restart (after running for few days) it is nulled again.
> I've never changed the default configuration of cassandra caches. What's going wrong? Thanks.

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