Hello, i found i have these values in mysql: mysql> show global status like 'open%'; +--------------------------+----------+ | Variable_name | Value | +--------------------------+----------+ | Open_files | 1101 | | Open_streams | 0 | | Open_table_definitions | 723 | | Open_tables | 728 | | Opened_files | 13114006 | | Opened_table_definitions | 7276634 | | Opened_tables | 3825856 | +--------------------------+----------+ In this article, author suggested it can be good idea to calculate proper Table_open_cache value this way: Table_open_cache = total_tables*Threads_connected I see i have 13658 total tables in databases and around 10 threads at a time, so should i set Table_open_cache to this value safely? 140000 (140,000) cant happen that server fatally fail because of no RAM or no SWAP (i have vswap) ? Thx Update: mysql says this: So "MySQL may run out of file descriptors and refuse connections, fail to perform queries, and be very unreliable." if i set it too high.. but how to discover what value is too high? # cat /proc/sys/fs/file-max 2451492 my filesystem # df | grep -v virtfs Filesystem 1K-blocks Used Available Use% Mounted on /dev/simfs 358400000 223243064 135156936 63% /