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https://issues.apache.org/jira/browse/IGNITE-7730?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Denis Magda reassigned IGNITE-7730:
-----------------------------------
Assignee: Artem Budnikov (was: Denis Magda)
> 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: Artem Budnikov
> Priority: Major
> Fix For: 2.7
>
>
> 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
> 1. average load or
> 2. 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}
> One more note from [~ivan.glukos] on dev.list we need to include. It is
> answer to question how user can determine if segment from archive folder can
> be safely removed:
> {quote}
> By the way: WAL compression is already implemented that way. If there
> are any ".zip" segments in archive dir, they are free to delete.
> This can be a safe workaround for users who experience lack of free
> space - just delete compressed segments. We should mention it in
> documentation for 2.4 release.
> {quote}
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