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From Kristopher Kane <>
Subject Re: Write ahead log growth and reduction
Date Wed, 11 Apr 2012 15:02:57 GMT
On Wed, Apr 11, 2012 at 10:48 AM, Keith Turner <> wrote:

> How big is the partition?  Are the same number of logger servers
> running as tablet servers?
> You can scan the metadata table to look for tablets that have alot of
> write-ahead logs. I think the command below will show you how many
> write-ahead logs each tablet has.  Look for any tablets that have too
> many. I think it should sort the tablets with the most tablets to the
> top, but not positive.
>   ./bin/accumulo shell -u root -p secret -e 'scan -t !METADATA -c
> log' | cut -f 1 -d ' ' | uniq -c  | sort -r -n
> I think the following command will show you how many active log each
> logger has.  This should be even.
>   ./bin/accumulo shell -u root -p secret -e 'scan -t !METADATA -c
> log' | cut -f 2 -d ' ' | cut -d ':' -f 2 | sort | uniq -c
> You can use the "flush -p" command in the shell to force data in
> memory to disk and stop referencing write-ahead logs.  Maybe execute
> the commands above before and after flushing.
> Keith

Thanks for the replies.  I read about the flush command in the docs but
didn't make a connection between "memory" to the write ahead logs.  Is
that correct?  Flush writes write ahead log data to hdfs?



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