The configuration files are located in the etc subdirectories (i.e. /opt/local/dalmatiner-db/etc/ddb.conf) of the applications, please consult the inline documentation for details about configuration parameters this document will only cover the most important ones.

Configuration File

points_per_file

The number of data points per metric per file. This is unrelated to the resolution of you have 604800 points per file with a 1s resolution a file stores a week of data, if you use 1m resolution it is 60 weeks of data.

cache_points

The datapoints per metric that are kept in memory before they are written to disk, this lets you tune the tradeoff between memory consumption and throughput. More cache points, mean more memory consumption but less disk IO (and thus higher throughput)

lifetime

The default how long data is kept around. This is an approximate value and can be tuned per bucket. An lifetime of infinity means data will never be discarded, any other value references to data points kept.

It needs to be noted that the lifetime is NOT a strict value it will only collect entire data files not partial data. In other words, if a datafile keeps 1 week of data a lifetime of everything less then 1 week will have the same effect then the lifetime of 1 week. The most sensible values to picks are multiples of the points per file.

vacuum_interval

Configures how the often vacuum process will pick a locally owned partition and discard old data-files. With 4 nodes, and 64 vnodes a 1 hour interval will mean that every 16 hours the entire vnode space is covered.

Runtime Configuration

ddb-admin ttl <bucket> 1w

Set the lifetime of a bucket, either in the buckets native time b using a simple number or in relative time by using a suffix like 'w' 's' 'h'. This value can be changed at any time.