Nagios資料庫引數配置分析

urgel_babay發表於2016-05-11
Nagios資料庫引數配置分析


MySQL 5.1.66             uptime 24 11:19:10     Fri Dec 26 09:54:55 2014


__ Key _________________________________________________________________
Buffer used     6.54M of   8.00M  %Used:  81.75
  Current       8.00M            %Usage: 100.00       //使用值相當高
Write hit      28.28%
Read hit       88.68%

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調整key_buffer_size值 大小:128M

1.單個key_buffer的大小不能超過4G,如果設定超過4G,就有可能遇到bug:
2.建議key_buffer設定為實體記憶體的1/4(針對MyISAM引擎),甚至是實體記憶體的30%~40%,
  如果key_buffer_size設定太大,系統就會頻繁的換頁,降低系統效能。
  因為MySQL使用作業系統的快取來快取資料,所以我們得為系統留夠足夠的記憶體;在很多情況下資料要比索引大得多。
3.如果機器效能優越,可以設定多個key_buffer,分別讓不同的key_buffer來快取專門的索引

深入地最佳化key_buffer_size,
使用"show status"來檢視"Key_read_requests, Key_reads, Key_write_requests  以及Key_writes ",
以調整到更適合你的應用的大小,Key_reads/Key_read_requests的大小正常情況下得小於0.01

| Key_read_requests      | 5262843294 |
| Key_reads              | 596037039  |       Key_reads/Key_read_requests 0.1相當不合理       

3.如果Handler_read_rnd太大,則你寫的SQL語句裡很多查詢都是要掃描整個表,而沒有發揮鍵的作用
4.如果Threads_created太大,就要增加my.cnf中thread_cache_size的值.可以用Threads_created/Connections計算cache命中率
5.如果Created_tmp_disk_tables太大,就要增加my.cnf中tmp_table_size的值,用基於記憶體的臨時表代替基於磁碟的  
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__ Questions ___________________________________________________________
Total         848.10M   401.1/s
  DMS         817.00M   386.4/s  %Total:  96.33         //    Data manipulation statements
  Com_         29.51M    14.0/s            3.48
  COM_QUIT      3.76M     1.8/s            0.44
  -Unknown      2.17M     1.0/s            0.26
Slow 10 s         112     0.0/s            0.00  %DMS:   0.00  Log: OFF       //慢查詢少

DMS           817.00M   386.4/s           96.33
  INSERT      551.05M   260.6/s           64.97         67.45
  SELECT      128.04M    60.6/s           15.10         15.67
  DELETE      102.56M    48.5/s           12.09         12.55
  UPDATE       35.23M    16.7/s            4.15          4.31
  REPLACE     109.88k     0.1/s            0.01          0.01
Com_           29.51M    14.0/s            3.48      //COM_ 這個類別代表著所有 MySQL 所執行過的指令,越小越好
  change_db    21.34M    10.1/s            2.52
  set_option    3.51M     1.7/s            0.41
  show_tables   2.42M     1.1/s            0.29




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資料庫寫讀比例大概是64:15
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__ SELECT and Sort _____________________________________________________
Scan           14.15M     6.7/s %SELECT:  11.05
Range           9.32M     4.4/s            7.28
Full join       6.17M     2.9/s            4.82
Range check         0       0/s            0.00
Full rng join     190     0.0/s            0.00
Sort scan       3.57M     1.7/s
Sort range    261.63k     0.1/s
Sort mrg pass      63     0.0/s



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注意Scan 與 Full Join。Scan 指的是有多少 SELECT statements 造成 MySQL 需要進行 Full Table Scan。
Full Join 的意思與 Scan 差不多,但它是適用在多個 Tables 相互 Join 在一起的情況
越小越好

進行scan佔全部select的11.05%      Full Join佔4.82%
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__ Table Locks _________________________________________________________
Waited        212.94k     0.1/s  %Total:   0.02     //代表 MySQL 需要等待以取得 table lock 的次數
Immediate     856.95M   405.3/s             //表示 MySQL 不需要等待即可立刻取得 table lock 的次數


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__ Tables ______________________________________________________________
Open               64 of   64    %Cache: 100.00           //table_cache已使用100%
Opened          1.93M     0.9/s


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table_cache必須增大。 目前: table_open_cache =64    調整,2000

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__ Connections _________________________________________________________
Max used           83 of 5000      %Max:   1.66
Total           3.76M     1.8/s


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nagios資料庫連線數不多,可以調低一些 500夠了
max_connections=500
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__ Created Temp ________________________________________________________
Disk table     39.99k     0.0/s
Table           6.15M     2.9/s    Size:  16.0M
File              131     0.0/s


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 Disk table 的值最好是三者中最小的一個。
 當暫時性的資料表被建立在硬碟中,表示此資料表沒有辦法被放進 RAM 裡面(因為 tmp_table_size 的值設得不夠大)。
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__ Threads _____________________________________________________________
Running             1 of   17
Cached              0 of    0      %Hit:      0
Created         3.76M     1.8/s
Slow                0       0/s


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thread_cache_size 的值需要調大,實際中 thread_cache_size 為0
 根據調查發現以上伺服器執行緒快取thread_cache_size沒有進行設定,或者設定過小,
 這個值表示可以重新利用儲存在快取中執行緒的數量,當斷開連線時如果快取中還有空間,
 那麼客戶端的執行緒將被放到快取中,如果執行緒重新被請求,那麼請求將從快取中讀取,如果
 快取中是空的或者是新的請求,那麼這個執行緒將被重新建立,如果有很多新的執行緒,增加這個
 值可以改善系統效能.透過比較 Connections 和 Threads_created 狀態的變數,可以看到這個變數
 的作用。
 (-->表示要調整的值)  根據實體記憶體設定規則如下:
     1G  ---> 8
     2G  ---> 16
     3G  ---> 32
    >3G  ---> 64
最佳化方法:
1、mysql> set global thread_cache_size=64
2、編輯/etc/my.cnf 更改/新增
thread_concurrency = 64

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__ Aborted _____________________________________________________________
Clients           160     0.0/s
Connects           10     0.0/s

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異常連線
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__ Bytes _______________________________________________________________
Sent          166.30G   78.7k/s
Received      558.75G  264.3k/s

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__ InnoDB Buffer Pool __________________________________________________
Usage           2.62G of   4.00G  %Used:  65.40
Read hit      100.00%
Pages
  Free         90.70k            %Total:  34.60        // Free指的是快取中的總頁數, 剩餘的頁, 佔總的34.60%
  Data        170.85k                     65.18 %Drty:   0.19       //Data是指快取中, 儲存索引資料的頁的數量
  Misc            590                      0.23
  Latched                                  0.00
Reads          49.93G   23.6k/s       //代表從快取裡, 總共讀取了多少M的資料.
  From file     3.71k     0.0/s            0.00
  Ahead Rnd        26     0.0/s      //表示隨機預讀的次數.
  Ahead Sql        13     0.0/s      //表示全表掃描時, sql預讀的次數.
Writes          7.77G    3.7k/s           //表示寫入快取的總大小
Flushes        24.43M    11.6/s           //表示快取資料更新到硬碟的大小.
Wait Free           0       0/s           //表示等待可寫入資料的頁的次數.


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innodb_buffer_pool_size=20G
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__ InnoDB Lock _________________________________________________________
Waits          481233     0.2/s
Current             0
Time acquiring
  Total       7054915 ms
  Average          14 ms
  Max           11949 ms

__ InnoDB Data, Pages, Rows ____________________________________________
Data
  Reads         4.34k     0.0/s
  Writes      555.01M   262.5/s
  fsync       548.99M   259.6/s
  Pending
    Reads           0
    Writes          0
    fsync           0

Pages
  Created     165.72k     0.1/s
  Read          5.14k     0.0/s
  Written      24.43M    11.6/s

Rows
  Deleted     115.26M    54.5/s
  Inserted    125.63M    59.4/s
  Read         17.01G    8.0k/s
  Updated     196.17M    92.8/s

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