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Mysqltuner output - advice
Posted by: rol and
Date: April 01, 2014 01:16PM

i have inherited the task of maintaining a mysql DB with amazon.
we're using mysql as an rds service from AWS.
i'm suffering from high lag between master and slave + max connections, so i decided to check my instance with mysqltuner.
i got interesting result, though some of them i did not get.
i hope you can guide me in the right direction in understanding whats given to me by mysqltuner:

------- Storage Engine Statistics -------------------------------------------
[--] Status: +Archive -BDB -Federated +InnoDB -ISAM -NDBCluster
[--] Data in MyISAM tables: 2G (Tables: 21)
[--] Data in InnoDB tables: 113G (Tables: 915)
[--] Data in MEMORY tables: 0B (Tables: 2)
[!!] Total fragmented tables: 485
-------- Performance Metrics -------------------------------------------------
[--] Up for: 31d 3h 53m 41s (302M q [112.267 qps], 70M conn, TX: 3882B, RX: 255B)
[--] Reads / Writes: 40% / 60%
[--] Total buffers: 11.1G global + 3.1M per thread (1263 max threads)
[!!] Maximum possible memory usage: 15.0G (102% of installed RAM)
[OK] Slow queries: 0% (130K/302M)
[!!] Highest connection usage: 100% (1266/1263)
[OK] Key buffer size / total MyISAM indexes: 16.0M/2.8G
[OK] Key buffer hit rate: 99.0% (12B cached / 123M reads)
[!!] Query cache is disabled
[OK] Sorts requiring temporary tables: 0% (1K temp sorts / 66M sorts)
[!!] Joins performed without indexes: 22671697
[OK] Temporary tables created on disk: 1% (1M on disk / 63M total)
[!!] Thread cache is disabled
[!!] Table cache hit rate: 0% (400 open / 1M opened)
[OK] Open file limit used: 0% (47/65K)
[OK] Table locks acquired immediately: 99% (700M immediate / 700M locks)
[!!] InnoDB data size / buffer pool: 113.0G/11.1G

-------- Recommendations -----------------------------------------------------
General recommendations:
(truncated to just show what i'm confused about)
Reduce or eliminate persistent connections to reduce connection usage
Adjust your join queries to always utilize indexes
Set thread_cache_size to 4 as a starting value
Increase table_cache gradually to avoid file descriptor limits



Any advice or hint on understanding the above, would be greatly appreciated



Edited 1 time(s). Last edit at 04/01/2014 01:22PM by rol and.

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