By Will Mayall

wamayall@yahoo.com

24-SEP-2014

1

Filesystem CheckThe first thing you need to know is that /var/lib/mysql/ibdata1 file NEVER shrinks!

We opted to enable innodb_file_per_table to bypass ibdata1 file from growing out of control.

However, the individual *.ibd files will grow, the optimize command will shrink the file, but will lock the table!

ls –ltr /apps/mysql_data/ > LS_MYSQL_24sep2014.doc

Also keep track of all the filesystems.df –h > DF_H_24sep2014.doc

2

Check Database SizesCheck the size of the databases daily.tee DATABASE_SIZES.docselect sysdate();SELECT table_schema "Data Base Name",sum( data_length + index_length ) / 1024 / 1024 "Data Base Size in MB",sum( data_free )/ 1024 / 1024 "Free Space in MB"

FROM information_schema.TABLESGROUP BY table_schema;

3

Verify Database Sizes

4

Data Base Name Data Base Size in MB Free Space in MB

MY_DB 7770.32812500 7.00000000

performance_schema

0.00000000 0.00000000

information_schema

0.00781250 0.00000000

mysql 0.77073860 0.09775925

24-sep-2014

Check the Number of UsersIt’s a good idea to know your users as you are their client. Therefore, get a daily count of users and compare it from the pervious day. Make a note of new users.

5

QUERY select count(*) from mysql.user;

COUNT 21

24-sep-2014

Check for Missing Passwordsmysql> select User,Password,Host from mysql.user where nullif(Password, '') is NULL;

+------+----------+-----------+ | User | Password | Host | +------+----------+-----------+ | root | | localhost | | root | | 127.0.0.1 | | root | | ::1 | +------+----------+-----------+ 3 rows in set (0.00 sec)

mysql>

6

Check the Growth of TablesIt’s a bad idea to do select count(*) of tables, but since this is a new application, knowing the table growth rate out weighs the performance hit.

mysqlshow -uUSER -p -t radius --count

7

Check the Global StatusDuring peak traffic, checking the global status can help identify variables that are being exceeded.

echo "show global status\G" | mysql -uUSER -p

8

Check the Global VariablesIt is good to verify the variables in the my.cnf actually were picked up.

echo "show global variables;" | mysql -uUSER -p

9

Show engine innodb statusFor innodb tables, getting a 60 second snapshot of the status can help identify problems.

mysql> show engine innodb status\Gselect sleep(60); show engine innodb status\G *************************** 1. row *************************** Type: InnoDB Name: Status: ===================================== 131206 21:04:28 INNODB MONITOR OUTPUT ===================================== Per second averages calculated from the last 27 seconds ----------------- BACKGROUND THREAD ----------------- srv_master_thread loops: 47785 1_second, 47438 sleeps, 4253 10_second, 17623 background, 17623 flush srv_master_thread log flush and writes: 50244

----------

10

Database Table StatusMySQL gathers Metadata about the status of the Tables.

mysql> show table status from radius\G *************************** 4. row *************************** Name: radcheck Engine: InnoDB Version: 10 Row_format: Compact Rows: 1 Avg_row_length: 16384 Data_length: 16384 Max_data_length: 0 Index_length: 16384 Data_free: 0 Auto_increment: 2 Create_time: 2013-11-17 01:30:32 Update_time: NULL Check_time: NULL Collation: latin1_swedish_ci Checksum: NULL Create_options: Comment:

11

Database Index Status MySQL gathers Metadata about the status of the Tables.

mysql> show index from radius.radacct\G *************************** 1. row *************************** Table: radacct Non_unique: 0 Key_name: PRIMARY Seq_in_index: 1 Column_name: radacctid Collation: A Cardinality: 15293918 Sub_part: NULL Packed: NULL Null: Index_type: BTREE Comment: Index_comment:

12

Identifying Indexes To check Indexes mysql> show create table radacct\G *************************** 1. row *************************** Table: radacct Create Table: CREATE TABLE `radacct` ( `radacctid` bigint(21) NOT NULL AUTO_INCREMENT, `acctsessionid` varchar(64) NOT NULL DEFAULT '', `acctuniqueid` varchar(32) NOT NULL DEFAULT '', `username` varchar(64) NOT NULL DEFAULT '', `groupname` varchar(64) NOT NULL DEFAULT '', `realm` varchar(64) DEFAULT '', `nasipaddress` varchar(15) NOT NULL DEFAULT '', `nasportid` varchar(15) DEFAULT NULL, `nasporttype` varchar(32) DEFAULT NULL, `acctstarttime` datetime DEFAULT NULL, `acctstoptime` datetime DEFAULT NULL, `acctsessiontime` int(12) DEFAULT NULL, `acctauthentic` varchar(32) DEFAULT NULL, `connectinfo_start` varchar(50) DEFAULT NULL, `connectinfo_stop` varchar(50) DEFAULT NULL, `acctinputoctets` bigint(20) DEFAULT NULL, `acctoutputoctets` bigint(20) DEFAULT NULL, `calledstationid` varchar(50) NOT NULL DEFAULT '', `callingstationid` varchar(50) NOT NULL DEFAULT '', `acctterminatecause` varchar(32) NOT NULL DEFAULT '', `servicetype` varchar(32) DEFAULT NULL, `framedprotocol` varchar(32) DEFAULT NULL, `framedipaddress` varchar(15) NOT NULL DEFAULT '', `acctstartdelay` int(12) DEFAULT NULL, `acctstopdelay` int(12) DEFAULT NULL, `xascendsessionsvrkey` varchar(10) DEFAULT NULL, PRIMARY KEY (`radacctid`), UNIQUE KEY `acctuniqueid` (`acctuniqueid`), KEY `username` (`username`), KEY `framedipaddress` (`framedipaddress`), KEY `acctsessionid` (`acctsessionid`), KEY `acctsessiontime` (`acctsessiontime`), KEY `acctstarttime` (`acctstarttime`), KEY `acctstoptime` (`acctstoptime`), KEY `nasipaddress` (`nasipaddress`) ) ENGINE=InnoDB AUTO_INCREMENT=23938867 DEFAULT CHARSET=latin1

13

Profiling a Query mysql> set profiling=1; Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> select nasipaddress,count(username),count(distinct username) from radacct group by nasipaddress;

+---------------+-----------------+--------------------------+ | nasipaddress | count(username) | count(distinct username) | +---------------+-----------------+--------------------------+ | 10.1.0.10 | 6046041 | 126298 | | 10.1.1.10 | 5778779 | 117265 | | 10.1.2.10 | 1075229 | 65161 | | 10.1.3.10 | 5187580 | 93745 | | 10.1.4.10 | 4727107 | 107447 | +---------------+-----------------+--------------------------+ 5 rows in set (37.91 sec)

14

Profiling a Query Continued mysql> show profile for query 1; +----------------------+-----------+ | Status | Duration | +----------------------+-----------+ | starting | 0.000054 | | checking permissions | 0.000007 | | Opening tables | 0.000011 | | init | 0.000014 | | System lock | 0.000008 | | optimizing | 0.000007 | | statistics | 0.000019 | | preparing | 0.000047 | | Sorting result | 0.000005 | | executing | 0.000004 | | Sending data | 37.915050 | | end | 0.000439 | | removing tmp table | 0.000013 | | end | 0.000007 | | query end | 0.000011 | | closing tables | 0.000016 | | freeing items | 0.000027 | | logging slow query | 0.000006 | | cleaning up | 0.000015 | +----------------------+-----------+ 19 rows in set, 1 warning (0.00 sec)

mysql>

15

ReplicationRow Based vs Statement Based ReplicationThe Default is Statement Based Replication which replays the exact SQL statement on the Slave. This is generally much slower than row based replication.

Row Based Replication inserts the returned values of the query executed on the Master.

16

Checking Replication mysql> show slave status\G *************************** 1. row *************************** Slave_IO_State: Queueing master event to the relay log Master_Host: mysql01-db Master_User: repl Master_Port: 3307 Connect_Retry: 60 Master_Log_File: blog.022416 Read_Master_Log_Pos: 861798108 Relay_Log_File: mysql02-relay-bin.002375 Relay_Log_Pos: 55290803 Relay_Master_Log_File: blog.022416 Slave_IO_Running: Yes Slave_SQL_Running: Yes Replicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 0 Last_Error: Skip_Counter: 0 Exec_Master_Log_Pos: 861797661 Relay_Log_Space: 189530366 Until_Condition: None Until_Log_File: Until_Log_Pos: 0 Master_SSL_Allowed: No Master_SSL_CA_File: Master_SSL_CA_Path: Master_SSL_Cert: Master_SSL_Cipher: Master_SSL_Key: Seconds_Behind_Master: 0 Master_SSL_Verify_Server_Cert: No Last_IO_Errno: 0 Last_IO_Error: Last_SQL_Errno: 0 Last_SQL_Error: Replicate_Ignore_Server_Ids: Master_Server_Id: 991

17

Repairing ReplicationIf Replication Breaks, you MIGHT be able to by-pass the error, otherwise you will have to rebuild Replication from the Master.

mysql>SET GLOBAL sql_slave_skip_counter = 1; mysql>start slave; mysql>show slave status\G

18

Helpful Unix Commands Get to know your filesystem (/etc/fstab), eg. ext3 vs ext4. fs_spec- desc FS, fs_file – desc mount point, fs_vfstype – desc the type of FS, fs_mntops – desc mount option, fs_freq – desc determines FS dump, fs_passno – used by fsck

To increase I/O performance change the fs_mntops from the defaults.

/dev/mapper/osvg-root / ext4 defaults 1 1

UUID=c96df9ac-787b-4388-9de9-74c292692f9b /boot ext3 defaults 1 2

/dev/mapper/osvg-opt /opt ext4 defaults 1 2

/dev/mapper/osvg-var /var ext4 defaults 1 2

/dev/mapper/appsvg-apps /apps ext4 defaults 1 2

/dev/sda2 /apps/full_backup ext4 defaults 1 2

tmpfs /dev/shm tmpfs defaults 0 0

devpts /dev/pts devpts gid=5,mode=620 0 0

sysfs /sys sysfs defaults 0 0

proc /proc proc defaults 0 0

LABEL=swap swap swap defaults 0 0

19

ext3 vs ext4ext3Introduced in 2001 ext3 supports journaling which improves speed. There are three levels of journaling for ext3 ” lowest, medium, highest ” risk check.

ext4With the stable release of ext4 in 2008, this becomes one of the best file system out there.  Transferring speed is really good, but it’s not depending on the file system itself, it also relies on hardware specifications, operating system, Kernel and many more dependencies.

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ext3 vs ext4

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Ext3 ext4

Stands For Third Extended Filesystem

Fourth Extended Filesystem

Original OS Linux Linux

Max Volume Size 256TB 1 EB

Max File Size 16GB – 2TB 16TB

Max Filename Length

254 bytes 256 bytes

Journaling Yes Yes

IOSTAT -dx iostat –dx 1 20 Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util sda 0.00 0.01 0.05 0.04 28.98 27.89 668.00 0.00 1.71 0.65 0.01 dm-0 0.01 83.08 0.03 24.24 2.22 819.96 33.88 0.03 1.36 0.90 2.18 dm-1 0.00 0.00 0.01 0.00 0.05 0.00 4.06 0.00 24.57 24.56 0.03 dm-2 0.01 14.16 0.05 4.13 2.20 144.24 35.01 0.08 18.36 1.75 0.73 dm-3 0.00 0.00 0.01 0.00 0.01 0.00 1.21 0.00 5.21 1.74 0.00 dm-4 0.00 0.00 0.01 0.00 0.51 0.00 35.39 0.00 4.39 4.02 0.01 dm-5 0.00 0.00 0.02 107.32 2.19 819.96 7.66 0.19 1.75 0.20 2.17 dm-6 0.00 0.00 0.00 0.00 0.02 0.00 5.35 0.00 6.55 3.70 0.00 dm-7 0.00 0.00 0.05 18.29 2.16 144.24 7.98 0.43 23.40 0.40 0.73 dm-8 0.00 0.00 0.01 0.00 0.49 0.00 40.33 0.00 4.52 3.53 0.00 dm-9 0.00 0.00 0.03 1.29 1.20 10.36 8.76 0.04 31.10 1.46 0.19 sdf 0.00 0.00 0.03 2.20 1.12 72.19 32.97 0.01 3.59 0.56 0.12 sdg 0.00 0.00 0.01 0.00 0.26 0.00 33.39 0.00 3.74 3.74 0.00 sdh 0.00 0.00 0.01 14.27 1.13 410.12 28.78 0.01 0.98 0.71 1.02 sdi 0.00 0.00 0.01 0.00 0.05 0.00 5.44 0.00 1.72 1.72 0.00 dm-10 0.00 0.00 0.00 0.00 0.48 0.00 99.96 0.00 7.45 5.03 0.00 dm-11 0.00 0.00 0.01 16.55 0.50 132.43 8.03 0.38 23.24 0.37 0.62 dm-12 0.00 0.00 0.01 0.18 0.40 1.46 9.77 0.00 17.27 8.02 0.15 dm-13 0.00 0.00 0.01 103.01 2.14 819.95 7.98 0.19 1.82 0.21 2.17 sdb 0.00 0.00 0.00 1.03 0.03 30.27 29.41 0.00 3.86 0.48 0.05 sdc 0.00 0.00 0.00 0.00 0.01 0.00 4.85 0.00 3.57 3.57 0.00 sdd 0.00 0.00 0.00 6.67 0.01 192.74 28.89 0.01 0.84 0.61 0.40 sde 0.00 0.00 0.00 0.00 0.01 0.00 8.00 0.00 1.66 1.66 0.00

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VMSTAT vmstat 1 20 procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 2 0 0 16705084 388 21434300 0 0 229 212 0 0 6 1 93 0 2 0 0 16657148 388 21434288 0 0 0 19 3436 3598 5 1 95 0 2 0 0 16657512 388 21434284 0 0 0 84 1897 1033 5 0 95 0 2 0 0 16657496 388 21434284 0 0 0 20 1298 955 4 0 95 0 4 0 0 16787144 388 21449080 0 0 0 492 2077 1281 5 1 94 0 1 0 0 16772468 384 21449096 0 0 1260 61007 6352 7445 1 3 96 0 17 0 0 17017212 388 21165932 0 0 5914 5017 42771 54745 17 10 72 1 10 0 0 17015168 388 21167964 0 0 1332 3589 33222 36175 27 8 65 0 6 0 0 17008832 388 21159076 0 0 420 564 31538 31344 31 4 65 0 8 0 0 16976264 388 21160504 0 0 6940 1132 22048 27035 21 4 75 0 8 0 0 16885008 388 21194688 0 0 17796 0 12144 5351 26 4 70 0 5 0 0 16951516 388 21179876 0 0 1888 5 10102 4534 20 4 76 0 4 0 0 16963556 388 21182392 0 0 2393 3579 9982 5255 12 3 85 0 4 0 0 16962976 388 21200324 0 0 18460 524 5825 2901 9 4 87 0 6 0 0 16950652 388 21201276 0 0 936 452 5669 3554 11 5 84 0 5 0 0 16919420 388 21219484 0 0 16796 0 8565 3730 13 4 83 0 2 0 0 16926496 388 21219432 0 0 56 207 5534 2509 13 5 82 0

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TOP You need to know MySQL pre-allocates Memory at startup. top top - 22:03:56 up 69 days, 20:02, 1 user, load average: 0.34, 0.26,

0.18 Tasks: 832 total, 1 running, 831 sleeping, 0 stopped, 0 zombie Cpu(s): 0.1%us, 0.4%sy, 0.0%ni, 99.6%id, 0.0%wa, 0.0%hi, 0.0%si,

0.0%st Mem: 264493968k total, 116693676k used, 147800292k free, 741404k

buffers Swap: 8393944k total, 0k used, 8393944k free, 101977944k cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 13299 root RT 0 458m 70m 42m S 4.3 0.0 982:15.40 corosync 3761 william. 20 0 15560 1840 948 R 0.7 0.0 0:00.11 top 58946 root 20 0 26216 1772 704 S 0.7 0.0 87:28.83 cmaperfd 8163 root 20 0 106m 2460 1208 S 0.3 0.0 80:31.19 scsm 15770 mysql 19 -1 22.8g 9.6g 7188 S 0.3 3.8 10178:15 mysqld 1 root 20 0 19228 1528 1236 S 0.0 0.0 8:08.60 init

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Checking the mysqld Threads wmayall@db50:~$ ps -ef |grep mysqld wmayall 19235 32139 0 08:46 pts/17 00:00:00 grep --color=auto mysqld root 29659 1 0 Sep23 pts/13 00:00:00 /bin/sh /opt/mysql/server-5.6/bin/mysqld_safe --datadir=/mysql --pid-file=/mysql/db50.pid mysql 30487 29659 99 Sep23 pts/13 14:45:21 /opt/mysql/server-5.6/bin/mysqld --basedir=/opt/mysql/server-5.6 --datadir=/mysql --plugin-dir=/opt/mysql/server-5.6/lib/plugin --

user=mysql --log-error=/mysql/db50.err --pid-file=/mysql/db50.pid --socket=/tmp/mysql.sock --port=3306 wmayall@db50:~$

wmayall@db50:~$ top -p 30487 –H

top - 08:49:16 up 209 days, 17:38, 11 users, load average: 14.38, 5.90, 4.22 Tasks: 182 total, 24 running, 158 sleeping, 0 stopped, 0 zombie Cpu(s): 58.5%us, 31.1%sy, 0.0%ni, 10.2%id, 0.0%wa, 0.0%hi, 0.1%si, 0.0%st Mem: 65943808k total, 49776144k used, 16167664k free, 388k buffers Swap: 10485756k total, 0k used, 10485756k free, 21920948k cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 30807 mysql 20 0 32.9g 7.8g 12m R 90 12.4 4:53.30 mysqld 18728 mysql 20 0 32.9g 7.8g 12m R 90 12.4 4:06.05 mysqld 30787 mysql 20 0 32.9g 7.8g 12m R 89 12.4 8:56.86 mysqld 10166 mysql 20 0 32.9g 7.8g 12m R 89 12.4 1:45.46 mysqld 10762 mysql 20 0 32.9g 7.8g 12m R 89 12.4 3:39.19 mysqld 16599 mysql 20 0 32.9g 7.8g 12m R 88 12.4 1:57.14 mysqld 10186 mysql 20 0 32.9g 7.8g 12m S 88 12.4 1:43.29 mysqld 10457 mysql 20 0 32.9g 7.8g 12m R 86 12.4 0:59.81 mysqld 30803 mysql 20 0 32.9g 7.8g 12m R 86 12.4 3:46.43 mysqld 30805 mysql 20 0 32.9g 7.8g 12m S 85 12.4 3:47.04 mysqld 10462 mysql 20 0 32.9g 7.8g 12m S 85 12.4 2:02.88 mysqld 30750 mysql 20 0 32.9g 7.8g 12m R 84 12.4 4:21.46 mysqld 10174 mysql 20 0 32.9g 7.8g 12m R 84 12.4 3:18.21 mysqld 16569 mysql 20 0 32.9g 7.8g 12m R 84 12.4 0:51.66 mysqld 30815 mysql 20 0 32.9g 7.8g 12m R 84 12.4 8:30.47 mysqld 10038 mysql 20 0 32.9g 7.8g 12m R 84 12.4 2:27.83 mysqld 30963 mysql 20 0 32.9g 7.8g 12m R 83 12.4 3:22.88 mysqld 16568 mysql 20 0 32.9g 7.8g 12m R 83 12.4 0:34.58 mysqld 9991 mysql 20 0 32.9g 7.8g 12m R 83 12.4 2:12.23 mysqld 30789 mysql 20 0 32.9g 7.8g 12m R 81 12.4 7:22.55 mysqld 16564 mysql 20 0 32.9g 7.8g 12m R 80 12.4 0:42.93 mysqld 30793 mysql 20 0 32.9g 7.8g 12m R 49 12.4 3:23.04 mysqld 30792 mysql 20 0 32.9g 7.8g 12m R 46 12.4 2:18.30 mysqld 30749 mysql 20 0 32.9g 7.8g 12m R 45 12.4 3:19.58 mysqld 16567 mysql 20 0 32.9g 7.8g 12m S 38 12.4 0:23.08 mysqld 10764 mysql 20 0 32.9g 7.8g 12m S 34 12.4 0:29.55 mysqld 10116 mysql 20 0 32.9g 7.8g 12m S 26 12.4 1:28.88 mysqld

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NETSTATNetstat can be used to help Identify who is accessing the database remotely.

netstat -ntp |grep :3306(No info could be read for "-p": geteuid()=1458 but you should be root.)

tcp 0 0 10.65.105.137:3306 10.71.0.25:33876 ESTABLISHED -

tcp 0 0 10.65.105.137:3306 10.75.0.24:45161 ESTABLISHED -

tcp 0 0 10.65.105.137:3306 10.74.0.24:50678 ESTABLISHED -

tcp 0 0 10.65.105.137:3306 10.72.0.25:56946 ESTABLISHED -

tcp 0 0 10.65.105.137:3306 10.73.0.25:46129 ESTABLISHED -

tcp 0 0 10.65.105.137:3306 10.65.103.183:51526 ESTABLISHED -

tcp 0 0 10.65.105.137:3306 10.73.0.24:58631 ESTABLISHED -

tcp 0 0 10.65.105.137:3306 10.71.0.24:34191 ESTABLISHED -

tcp 0 0 10.65.105.137:3306 10.75.0.25:33685 ESTABLISHED -

tcp 0 0 10.65.105.137:3306 10.74.0.25:41889 ESTABLISHED -

tcp 0 0 10.65.105.137:3306 10.72.0.24:48392 ESTABLISHED -

tcp 0 0 10.65.105.137:3306 10.65.103.182:46907 ESTABLISHED -

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MySQL Performance TuningThe Default MySQL Configuration file is too small for most Applications. There are a handful of parameters that will make your life as a DBA have more time to surf the web instead of doing DBA work. The following changes should give you the most performance boost.

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MySQL Configuration FileThe my.cnf file can live where ever you point it to.

PROD mysqlaaa01.prod:william.mayall[~/scripts]$ locate my.cnf /apps/scripts/.my.cnf /apps/scripts/my.cnf /apps/scripts/copy_env/.my.cnf /etc/my.cnf /home/william.mayall/.my.cnf /home/william.mayall/my.cnf /home/william.mayall/my.cnf.05aug2013 /home/william.mayall/copy_env/.my.cnf /usr/my.cnf

Which my.cnf do you chose? PROD mysqlaaa01.prod:william.mayall[~/scripts]$ ps -ef |grep mysql root 15365 1 0 Sep30 ? 00:00:00 /bin/sh /usr/bin/mysqld_safe

--defaults-file=/usr/my.cnf --pid-file=/var/run/cluster/mysql/mysql:mysql_conf.pid --bind-address=10.65.105.137

mysql 15770 15365 10 Sep30 ? 7-01:38:30 /usr/sbin/mysqld --defaults-file=/usr/my.cnf --basedir=/usr --datadir=/apps/mysql_data --plugin-dir=/usr/lib64/mysql/plugin --user=mysql --bind-address=10.65.105.137 --log-error=/var/log/mysql/mysql.er --pid-file=/var/run/cluster/mysql/mysql:mysql_conf.pid

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MySQL Configuration File #cat /usr/my.cnf /usr/my.cnf [mysqld] basedir=/usr datadir=/apps/mysql_data plugin-dir=/usr/lib64/mysql/plugin user=mysql log-error=/var/lib/mysql/mysql.err pid-file=/var/lib/mysql/mysql.pid ignore-db-dir=lost+found log-bin=mysqld-bin server-id=10 max_allowed_packet=128M max_connections=1000 expire_logs_days=4 Back_log=400 binlog_cache_size = 8388608 bulk_insert_buffer_size = 268435456 innodb_buffer_pool_size = 17179869184 innodb_flush_log_at_trx_commit = 2 key_buffer_size = 2147483648 max_heap_table_size = 33554432 thread_cache_size = 30 tmp_table_size = 33554432 innodb_log_file_size = 134217728 innodb_file_per_table = 1 [mysqld_safe] basedir=/usr datadir=/apps/mysql_data pid-file=/var/log/mysql/mysql.pid log-error=/var/log/mysql/mysql.er

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innodb_flush_log_at_trx_commit For I/O Bound performance changing this parameter from 1 to 2 will give you the best performance increase.

The Default value of 1 means each update transaction commits (or each statement outside of the transaction) will need to flush log to the disk which is rather expensive, especially if you do not have Battery backed up cache. Many applications are OK with this value set to 2 which means do not flush log to the disk, but only flush it to OS cache. The log is still flushed to the disk each second so you normally would not lose more than 1-2 seconds worth of updates. Value 0 is a bit faster but is a bit less secure as you can lose transactions even in case MySQL Server crashes. The value set to 2 only causes data loss with full OS crash without battery backed up RAM or Disks.

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innodb_log_file_size I’ve seen innodb_log_file_size to be the second best performance increaser.

Very important for write intensive workloads especially for large data sets. Larger sizes offer better performance but increases recovery times so be careful. I normally use values 64M-512M depending on server size. The current size is 100M for db4, which is fine.

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innodb_buffer_pool_size Again, the default of 8M is just too small. This is like the SGA for Oracle. Would you create an 8M SGA for a 2GB Oracle database?

It is best practices to cache the entire database, there is no reason not to IF you have enough RAM.

Usually ¾ the Size of RAM, if the server is only using mysqld.

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key_buffer_size The key_buffer_size is for MyISAM Tables, including TEMP & Memory Tables.

Tmp_table_size Max_heap_size The max_heap_size must be equal to or greater than the tmp_table_size.

If you can, make it as large as all combined Indexes plus tmp_table_size and max_heap_size.

If possible, make it as large as all combined Indexes.

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key_cache_block_sizeMyISAM uses the Operating Block Size, which is normally 4096 bytes.

MySQL Default is usually 1024 Bytes.To speed up large MyISAM queries increasing the key_cache_block_size to 4096 will increase performance.

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back_logIf you are experiencing web service thrashing (high loads), increase the back_log value higher than or equal to 400.

Drawbacks are the web server will accept new connections, and the database server can become saturated.

35

max_allowed_packetThe default of 1MB is too small, genereally make the max_allowed_packet 16MB – 256MB.

The Slave variables should be greater or equal to the Master’s variables.

36

table_open_cache This is a tricky one. You can actually see a performance hit if you get this wrong!

Increase it gradually over time, check “SHOW GLOBAL STATUS” check the Opened_tables value, you do NOT want Opened_tables increasing during peak times.

I suggest setting the value to 128 and go from there. It currently is set to 64 on db4.

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query_cache_size The Query Cache will put often used queries into cache.

I noticed the user queries using the NO_CACHE Hint, but enabling cache could be of benefit to Ad-Hoc queries.

I suggest setting the value to 8M. It is currently disabled in db4.

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Cache Hit Rates How to calculate cache hit rates mysql> show global status like 'Qc%'; +-------------------------+-----------+ | Variable_name | Value | +-------------------------+-----------+ | Qcache_free_blocks | 3671 | | Qcache_free_memory | 679977496 | | Qcache_hits | 3188949 | | Qcache_inserts | 3120018 | | Qcache_lowmem_prunes | 301732 | | Qcache_not_cached | 1066818 | | Qcache_queries_in_cache | 153203 | | Qcache_total_blocks | 314518 | +-------------------------+-----------+ 8 rows in set (0.00 sec)

mysql> show global status like 'Com_select%'; +---------------+---------+ | Variable_name | Value | +---------------+---------+ | Com_select | 5130462 | +---------------+---------+ 1 row in set (0.00 sec)

mysql> select 3188949/(3188949+5130462); +---------------------------+ | 3188949/(3188949+5130462) | +---------------------------+ | 0.3833 | +---------------------------+ 1 row in set (0.00 sec)

mysql>

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thread_cache_size Thread creation/destructions can be expensive, which happens at each connect/disconnect. I normally set this value to at least 16. If the application has large jumps in the amount of concurrent connections and when I see fast growth of Threads_created variable I set it higher. The goal is not to have threads created in normal operation.

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Scripts for Checking Bottlenecks Check iostat #!/bin/bash #Stolen from Will Mayall 25-Sep-2014 #./run_iostat.sh > IOSTAT_REPORT.doc & x=1 while [ $x -le 60 ] do echo "START RUN TIME" date /usr/bin/iostat -dx 1 20 x=$(( $x + 1 )) echo "END RUN TIME“ date sleep 60 done

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Scripts Continued Check vmstat #!/bin/bash #Stolen from Will Mayall 25-Sep-2014 #./run_vmstat.sh > VMSTAT_REPORT.doc & x=1 while [ $x -le 60 ] do echo "START RUN TIME" date /usr/bin/vmstat 1 20 x=$(( $x + 1 )) echo "END RUN TIME" date sleep 60 done

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Scripts Continued Show MySQL Status #!/bin/bash #Stolen from Will Mayall 25-Sep-2014 #./run_show_global_status.ksh > GLOBAL_STATUS_REPORT.doc &

x=1 while [ $x -le 60 ] do echo "START RUN TIME" date echo "show global status\G" | mysql -uUSER –pPASSWD x=$(( $x + 1 )) echo "END RUN TIME" date sleep 60 done

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Scripts Continued Show MySQL Full Processlist #!/bin/bash #Stolen from Will Mayall 25-Sep-2014 #./run_show_processlistsh > PROCESSLIST_REPORT.doc & x=1 while [ $x -le 60 ] do echo "START RUN TIME" date echo "show full processlist;" | mysql -uUSER –pPASSWD x=$(( $x + 1 )) echo "END RUN TIME“ date sleep 1 done

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Questions?

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