Dmitriy Pavlov created IGNITE-7730:
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Summary: Improve WAL history size documentation
Key: IGNITE-7730
URL: https://issues.apache.org/jira/browse/IGNITE-7730
Project: Ignite
Issue Type: Task
Components: documentation
Affects Versions: 2.1
Reporter: Dmitriy Pavlov
Assignee: Denis Magda
Fix For: 2.5
Until IGNITE-6552 is not implemented, we have only ability to configure WAL
hist. size in checkpoints.
It is needed to improve description for this parameter.
I've added draft notes to wiki
https://cwiki.apache.org/confluence/display/IGNITE/Ignite+Persistent+Store+-+under+the+hood#IgnitePersistentStore-underthehood-Estimatingdiskspace
about ways how wer can estimate WAL sizes without exact bytes/time
specification:
{panel}
WAL Work max used size: walSegmentSize * walSegments = 640Mb (default)
in case Default WAL mode - this size is used always,
in case other modes best case is 1 segment * walSegmentSize
WAL Work+WAL Archive max size may be estimated by
average load or
by maximum size.
1st way is applicable if checkpoints are triggered mostly by timer trigger.
Wal size = 2*Average load(bytes/sec) * trigger interval (sec) * walHistSize
(number of checkpoints)
Where 2 multiplier coming from physical & logical WAL Records.
2nd way: Checkpoint is triggered by segments max dirty pages percent. Use
persisted data regions max sizes:
sum(Max configured DataRegionConfiguration.maxSize) * 75% - est. maximum data
volume to be writen on 1 checkpoint.
Overall WAL size (before archiving) = 2* est. data volume * walHistSize = 1,5 *
sum(DataRegionConfiguration.maxSize) * walHistSize
Note applying WAL compressor may significiantly reduce archive size.
{panel}
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