MySQl: Specified key too long ..max is 1000 bytes

mysql     9804  0.0  0.6 58556 22960 pts/0   S    12:43   0:00  \_ /usr/sbin/mysqld --basedir=/ --datadir=/var/lib/mysql --user=mysql --pid-file=/var/lib/mysql/myhostname.pid --skip-external-locking --port=3306 --socket=/var/lib/mysql/mysql.sock
mysql     9807  0.0  0.6 58556 22960 pts/0   S    12:43   0:00      \_ /usr/sbin/mysqld --basedir=/ --datadir=/var/lib/mysql --user=mysql --pid-file=/var/lib/mysql/myhostname.pid --skip-external-locking --port=3306 --socket=/var/lib/mysql/mysql.sock
mysql     9808  0.0  0.6 58556 22960 pts/0   S    12:43   0:00          \_ /usr/sbin/mysqld --basedir=/ --datadir=/var/lib/mysql --user=mysql --pid-file=/var/lib/mysql/myhostname.pid --skip-external-locking --port=3306 --socket=/var/lib/mysql/mysql.sock
mysql     9809  0.0  0.6 58556 22960 pts/0   S    12:43   0:00          \_ /usr/sbin/mysqld --basedir=/ --datadir=/var/lib/mysql --user=mysql --pid-file=/var/lib/mysql/myhostname.pid --skip-external-locking --port=3306 --socket=/var/lib/mysql/mysql.sock
mysql     9810  0.0  0.6 58556 22960 pts/0   S    12:43   0:00          \_ /usr/sbin/mysqld --basedir=/ --datadir=/var/lib/mysql --user=mysql --pid-file=/var/lib/mysql/myhostname.pid --skip-external-locking --port=3306 --socket=/var/lib/mysql/mysql.sock
[ ... repeated output truncated ... ]

They're not using 13 * 50mb of ram -- They're probably using something like 70mb total. Remember that that linux will share unmodified memory pages between processes, so if your server is freshly started most of that memory would all be shared. In fact, since mysql is threaded there will only probably be even less memory allocated per thread. If you're concerned about the memory usage of each mysql process, look at /etc/mysql/my.cnf, and look at the variables in the mysqld section:

• key_buffers
• thread_stack
• thread_cache_size
• max_connections
• query_cache_limit
• query_cache_size

Be warned though, that those are very powerful variables to tune, and you can easily kill your mysql performance setting them too low, or waste memory that could be used elsewhere by setting them too high.

One easy starting point to figure out the best way to tune your mysql instance is to run your app for a little bit, then run the mysqltune script, which will analyze your performance counters, then produce a recommendation on what you should change in your server config.

innodb_buffer_pool_size > 1G, because your dataset size is 1,8GB.

To decrease number of reads you need to increase innodb_buffer_pool_size. To decrease number of writes you need to edit your zabbix templates (disabling some unnecessary items like free inodes, increase intervals between checks).

You have Reads / Writes ratio at 57% / 43%, so enabling Query Cache will not help (it may make things worse, because writes to tables invalidates cache).

Think about increasing tmp_table_size and max_heap_table_size to avoid creating tmp tables on disk (13% of tmp tables). Temporary tables are in MB? it is count? If it is counter, its too high.

Decrease number of connection to 50 (your highest number was 33).

innodb_support_xa = false
innodb_buffer_pool_size = 256M # It depends how many memory is available to MySQL, more is better.
innodb_flush_log_at_trx_commit = 0 # disable writing to logs on every commit and disable fsync on each write
innodb_max_dirty_pages_pct = 90 # avoid flushing dirty pages to disk
innodb_flush_method = O_DIRECT # direct access to disk without OS cache
thread_cache_size = 4
query_cache_size = 0
table_cache = 80? # a little more than number_of_tables_in_zabbix_database

Usefull link about InnoDB optimization.