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Date: Fri, 13 Jun 2014 18:05:02 +0000 (UTC)
From: "stack (JIRA)" <jira@apache.org>
To: issues@hbase.apache.org
Message-ID: <JIRA.12641752.1365555802516.128567.1402682702795@arcas>
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Subject: [jira] [Resolved] (HBASE-8315) Documentation should have more
 information of LRU Stats
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     [ https://issues.apache.org/jira/browse/HBASE-8315?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

stack resolved HBASE-8315.
--------------------------

       Resolution: Fixed
    Fix Version/s: 0.99.0

Committed small text change in UI and committed to master.

> Documentation should have more information of LRU Stats
> -------------------------------------------------------
>
>                 Key: HBASE-8315
>                 URL: https://issues.apache.org/jira/browse/HBASE-8315
>             Project: HBase
>          Issue Type: Improvement
>          Components: documentation
>    Affects Versions: 0.95.0
>            Reporter: Daisuke Kobayashi
>            Assignee: Misty Stanley-Jones
>              Labels: documentation
>             Fix For: 0.99.0
>
>         Attachments: 8351.txt, Screen Shot 2014-06-13 at 10.59.05 AM.png
>
>
> Unfortunately, there's no documentation to explain the meaning of each LRU Stats in the regionserver logs.  So this is for creating a new paragraph regarding this.  My current idea is below, but it's a little bit difficult to explain the difference between 'cachingAccesses' and 'accesses' from an administrator or a user views.
> Could you guys help to improve the content?
> {noformat}
> total: The current memory size of the cache in use.
> free: The total free memory currently available to store more cache entries.
> max: Maximum allowed memory size of the cache.
> blocks: Caches store blocks of data; this number is the current # of blocks stored, which use up the "total" memory space.
> accesses: The total number of times the cache was accessed, regardless of result.
> hits: The total number of times the cache was accessed and the result was a successful hit (presence of looked up element in cache is a hit).
> hitRatio: The current percentage for "hits / accesses".
> ====
> Unclear:
> cachingAccesses: cachingHits + The number of getBlock requests that were cache misses, but only from requests that were set to use the block cache.
> cachingHits: The number of getBlock requests that were cache hits, but only from requests that were set to use the block cache. This is because all reads
> =====
> cachingHitsRatio: The current percentage for "cachintHits / cachingAccesses"
> evictions: The total number of times an eviction has occurred (based on the use of the LRU algorithm)
> evicted: The total number of blocks that have been evicted (based on the use of the LRU algorithm)
> evictedPerRun: The total number of blocks that have been evicted overall / The number of times an eviction has occurred overall
> {noformat}
> And also, where should we add this paragraph in the documentation?


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