Update change-metrics-storage.md (#14834)
- Shorten sample calculations to display better on learn - Improve titles
Chris Akritidis committed
Mar 29, 2023 at 07:17 UTC
657da78ed1da829941272d6c6c850b3cbd5280a1
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docs/store/change-metrics-storage.md
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@@ -9,7 +9,7 @@ on the maximum retention and the memory used by Netdata is described in detail,
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## Calculate the system resources (RAM, disk space) needed to store metrics
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-### Disk space allocated to each tier
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+### Effect of storage tiers and disk space on retention
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3 tiers are enabled by default in Netdata, with the following configuration:
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@@ -52,19 +52,19 @@ about **1 byte per data point on disk for tier 0**, and **4 bytes per data point
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So, for 1000 metrics collected per second and 256 MB for tier 0, Netdata will store about:
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```
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-256MB on disk / 1 byte per point / 1000 metrics => 256k points per metric / 86400 seconds per day = about 3 days
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+256MB on disk / 1 byte per point / 1000 metrics => 256k points per metric / 86400 sec per day ~= 3 days
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```
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At tier 1 (per minute):
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```
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-128MB on disk / 4 bytes per point / 1000 metrics => 32k points per metric / (24 hours * 60 minutes) = about 22 days
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+128MB on disk / 4 bytes per point / 1000 metrics => 32k points per metric / (24 hr * 60 min) ~= 22 days
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```
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At tier 2 (per hour):
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```
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-64MB on disk / 4 bytes per point / 1000 metrics => 16k points per metric / 24 hours per day = about 2 years
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+64MB on disk / 4 bytes per point / 1000 metrics => 16k points per metric / 24 hr per day ~= 2 years
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```
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Of course double the metrics, half the retention. There are more factors that affect retention. The number
@@ -74,7 +74,7 @@ through time (because it has to break pages prematurely, increasing the metadata
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numbers should not deviate significantly from the above.
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-### Memory for concurrently collected metrics
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+### Effect of storage tiers and retention on memory usage
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The total memory Netdata uses is heavily influenced by the memory consumed by the DBENGINE.
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The DBENGINE memory is related to the number of metrics concurrently being collected, the retention of the metrics