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https://issues.apache.org/jira/browse/HBASE-2821?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Todd Lipcon updated HBASE-2821:
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Attachment: storefile_age.pl
Here's the script I used to parse the NN log.
Then I loaded into R and did something like:
{code}
d <- read.table(file="/tmp/lifetimes-nosplits.txt", header=F)
names(d) <- c("path", "type", "life")
library(ggplot2)
qplot(life, data=subset(d, life<9000), facets=type~., binwidth=10)
{code}
> Keep young storefiles at lower replication
> ------------------------------------------
>
> Key: HBASE-2821
> URL: https://issues.apache.org/jira/browse/HBASE-2821
> Project: HBase
> Issue Type: Improvement
> Components: regionserver
> Reporter: Todd Lipcon
> Attachments: lifetime-distribution.png, storefile_age.pl
>
>
> jgray and I were brainstorming some ideas about this:
> In a typical heavy-write scenario, many store files do not last very long.
> They're flushed and then within a small number of seconds a compaction runs
> and they get deleted. For these "short lifetime" store files, it's less
> likely that a failure will occur during the window in which they're valid.
> So, I think we can consider some optimizations like the following:
> - Flush files at replication count 2. Scan once a minute for any store files
> in the region that are older than 2 minutes. If they're found, increase their
> replication to 3. (alternatively, queue them to avoid scanning)
> - More dangerous: flush files at replication count 1, but don't count them
> when figuring log expiration. So, if they get lost, we force log splitting to
> recover.
> The performance gain here is that we avoid the network and disk transfer of
> writing the third replica for a file that we're just about to delete anyway.
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