Use new tier-based dbengine config

This might have an impact on disk usage for nodes with many incoming streams.

defaults/main.yml

 ---
 netdata_master: false
-netdata_page_cache_size: 256
-netdata_dbengine_disk_space: 1024
 netdata_health_configs:
   - apache.conf
   - go.d.plugin.conf
@@ -13,3 +11,11 @@ netdata_disable_last_collected_alerts: false
 netdata_enable_ebpf: true
 netdata_use_msmtp: true
 netdata_global_health_override: ""
+
+# See https://learn.netdata.cloud/docs/netdata-agent/configuration/optimizing-metrics-database/change-how-long-netdata-stores-metrics#retention-settings
+netdata_dbengine_tier0_disk_space: 0
+netdata_dbengine_tier0_retention_days: 14
+netdata_dbengine_tier1_disk_space: 0
+netdata_dbengine_tier1_retention_days: 90
+netdata_dbengine_tier2_disk_space: 0
+netdata_dbengine_tier2_retention_days: 730

templates/netdata.conf.j2

@@ -7,9 +7,23 @@
 
     {% if netdata_cache_directory is defined %}cache directory = {{ netdata_cache_directory }}{% endif %}
 
-    memory mode = dbengine
-    page cache size = {{ netdata_page_cache_size }}
-    dbengine multihost disk space = {{ netdata_dbengine_disk_space }}
+[db]
+    # https://learn.netdata.cloud/docs/netdata-agent/configuration/optimizing-metrics-database/change-how-long-netdata-stores-metrics#retention-settings
+    mode = dbengine
+    storage tiers = 3
+
+    # Tier 0, per second data
+    dbengine tier 0 disk space MB = {{ netdata_dbengine_tier0_disk_space }}
+    dbengine tier 0 retention days = {{ netdata_dbengine_tier0_retention_days }}
+
+    # Tier 1, per minute data
+    dbengine tier 1 disk space MB = {{ netdata_dbengine_tier1_disk_space }}
+    dbengine tier 1 retention days = {{ netdata_dbengine_tier1_retention_days }}
+
+    # Tier 2, per hour data
+    dbengine tier 2 disk space MB = {{ netdata_dbengine_tier2_disk_space }}
+    dbengine tier 2 retention days = {{ netdata_dbengine_tier2_retention_days }}
+
 {% if ansible_os_family == 'Debian' %}
 [web]
     web files owner = root