I cannot rule out a failing reverse DNS lookup, but all connections should be from within our local net where all hosts are known by /etc/hosts. Here's my my.cnf and output of pt-summary of our current running server. [client] port = 3306 socket = /tmp/mysql.sock [mysqld] port = 3306 socket = /tmp/mysql.sock skip-external-locking key_buffer_size = 1G max_allowed_packet = 32M user=sql datadir=/usr/local/mysql/data tmpdir=/usr/local/mysql/var read_buffer_size = 256K sort_buffer_size = 48M read_rnd_buffer_size = 256K join_buffer_size = 16M wait_timeout = 3 tmp_table_size = 256M max_heap_table_size = 256M thread_cache_size = 8 query_cache_size = 128M query_cache_limit = 16M max_connections = 500 max_join_size = 4G memlock ft_min_word_len = 2 myisam_sort_buffer_size = 512M open_files_limit=65535 table_open_cache=4096 log_error = datahost.err slow_query_log = off pid_file = /var/run/mysql.pid server_id = 304 expire_logs_days= 1 innodb_locks_unsafe_for_binlog = 1 innodb_data_home_dir = /usr/local/mysql/innodb/data/ innodb_data_file_path = ibdata1:100M:autoextend innodb_log_group_home_dir = /usr/local/mysql/innodb/var/ innodb_mirrored_log_groups = 1 innodb_log_files_in_group = 3 innodb_log_file_size = 1G innodb_log_buffer_size = 32M innodb_buffer_pool_size = 20G innodb_additional_mem_pool_size = 16M innodb_lock_wait_timeout = 300 innodb_file_per_table innodb_io_capacity = 750 innodb_flush_log_at_trx_commit = 1 tmpdir = /usr/local/mysql/var loose_handlersocket_port = 9998 loose_handlersocket_port_wr = 9999 loose_handlersocket_threads = 16 loose_handlersocket_threads_wr = 1 [mysqldump] quick max_allowed_packet = 16M [mysql] no-auto-rehash [isamchk] key_buffer_size = 256M sort_buffer = 256M read_buffer = 2M write_buffer = 2M [myisamchk] key_buffer_size = 512M sort_buffer = 512M read_buffer = 16M write_buffer = 16M [mysqlhotcopy] interactive-timeout [mysqld_safe] pid-file = /var/run/mysql/mysqld.pid open_files_limit=32768 # Percona Toolkit System Summary Report ###################### Date | 2015-03-17 15:44:28 UTC (local TZ: CET +0100) Hostname | datahost Uptime | 176 days, 5:23, 3 users, load average: 11.02, 11.60, 11.85 System | Supermicro; X8DTU; v1234567890 (Main Server Chassis) Service Tag | 1234567890 Platform | Linux Release | NAME=Slackware Kernel | 3.2.45 Architecture | CPU = 64-bit, OS = 64-bit Threading | NPTL 2.20 Compiler | GNU CC version 4.8.3. SELinux | No SELinux detected Virtualized | No virtualization detected # Processor ################################################## Processors | physical = 2, cores = 8, virtual = 16, hyperthreading = yes Speeds | 16x2399.824 Models | 16xIntel(R) Xeon(R) CPU E5620 @ 2.40GHz Caches | 16x12288 KB # Memory ##################################################### Total | 31.4G Free | 1.3G Used | physical = 30.1G, swap allocated = 7.6G, swap used = 247.1M, virtual = 30.3G Buffers | 4.6M Caches | 2.6G Dirty | 1032 kB UsedRSS | 26.6G Swappiness | 60 DirtyPolicy | 20, 10 DirtyStatus | 0, 0 Locator Size Speed Form Factor Type Type Detail ========= ======== ================= ============= ============= =========== BIOS 4096 kB 33 MHz Other Flash Non-Volatile P0_DIMM1A 8192 MB 1066 MHz DIMM Other Other P0_DIMM2A 8192 MB 1066 MHz DIMM Other Other P1_DIMM1A 8192 MB 1066 MHz DIMM Other Other P1_DIMM2A 8192 MB 1066 MHz DIMM Other Other P0_DIMM1B {EMPTY} Unknown DIMM Other Other P0_DIMM2B {EMPTY} Unknown DIMM Other Other P0_DIMM3A {EMPTY} Unknown DIMM Other Other P0_DIMM3B {EMPTY} Unknown DIMM Other Other P1_DIMM1B {EMPTY} Unknown DIMM Other Other P1_DIMM2B {EMPTY} Unknown DIMM Other Other P1_DIMM3A {EMPTY} Unknown DIMM Other Other P1_DIMM3B {EMPTY} Unknown DIMM Other Other # Mounted Filesystems ######################################## Filesystem Size Used Type Opts Mountpoint /dev/drbd1 536G 76% xfs rw,noatime,nodiratime /local.mnt/vol0 /dev/sda1 958M 42% ext3 rw / /dev/sda3 958M 13% ext3 rw /var /dev/sda5 9.4G 80% ext3 rw /usr /dev/sda6 3.7G 3% ext3 rw /home tmpfs 16G 0% tmpfs rw /dev/shm # Disk Schedulers And Queue Size ############################# drbd1 | 128 sda | [cfq] 128 # Disk Partioning ############################################ Device Type Start End Size ============ ==== ========== ========== ================== /dev/drbd1 Disk 575511011328 /dev/sda Disk 599998857216 /dev/sda1 Part 63 1992059 1019901952 /dev/sda2 Part 1992060 17992799 8192378368 /dev/sda3 Part 17992800 19984859 1019934208 /dev/sda4 Part 19984860 1171872767 589766608384 /dev/sda5 Part 19984923 39985784 10240440832 /dev/sda6 Part 39985848 47793374 3997453312 /dev/sda7 Part 47793438 1171872767 575528616448 # Kernel Inode State ######################################### dentry-state | 65618 59883 45 0 0 0 file-nr | 1376 0 786008 inode-nr | 74345 16582 # LVM Volumes ################################################ Unable to collect information # LVM Volume Groups ########################################## Unable to collect information # RAID Controller ############################################ Controller | Areca Technology Corp. ARC-1680 8 port PCIe/PCI-X to SAS/SATA II RAID Controller # Network Config ############################################# Controller | Intel Corporation 82576 Gigabit Network Connection (rev 01) Controller | Intel Corporation 82576 Gigabit Network Connection (rev 01) Controller | Intel Corporation 82576 Gigabit Network Connection (rev 01) Controller | Intel Corporation 82576 Gigabit Network Connection (rev 01) FIN Timeout | 60 Port Range | 61000 # Interface Statistics ####################################### interface rx_bytes rx_packets rx_errors tx_bytes tx_packets tx_errors ========= ========= ========== ========== ========== ========== ========== lo 1500000000 600000 0 1500000000 600000 0 eth0 20000000000000 35000000000 70 225000000000000 60000000000 0 eth1 7000000000000 15000000000 0 8000000000000 6000000000 0 eth2 150000000000000 50000000000 2 450000000000000 70000000000 0 eth3 150000000000000 50000000000 4 450000000000000 70000000000 0 bond0 25000000000000 50000000000 70 225000000000000 60000000000 0 bond1 300000000000000 100000000000 6 900000000000000 125000000000 0 vlan100@bond0 25000000000000 45000000000 0 225000000000000 60000000000 0 vlan200@bond0 800000000 12500000 0 1250000000 2500000 0 # Network Devices ############################################ Device Speed Duplex ========= ========= ========= bond0 eth0 1000Mb/s Full bond1 eth1 1000Mb/s Full eth2 1000Mb/s Full eth3 1000Mb/s Full # Network Connections ######################################## Connections from remote IP addresses 10.0.0.1 3 10.0.0.7 2 10.0.0.10 4 10.0.0.19 1 10.0.0.21 35 10.0.0.26 8 10.0.0.29 80 10.0.0.30 90 10.0.0.31 100 10.0.0.32 100 10.0.0.50 1 10.0.0.52 60 10.0.0.53 20 10.0.0.54 30 10.0.0.55 20 10.0.0.56 700 10.0.0.57 1000 10.0.0.85 35 10.0.0.86 60 10.0.0.87 30 10.0.0.88 30 10.0.0.96 45 10.0.0.97 30 10.0.0.98 20 10.0.0.99 45 10.0.0.190 80 10.0.0.191 50 10.0.0.192 50 10.0.0.193 150 10.0.0.197 15 10.0.0.199 7 10.0.0.216 80 10.0.0.217 35 10.0.0.218 35 10.0.0.219 70 10.0.0.225 300 10.0.0.226 450 10.0.0.236 30 10.0.0.237 100 10.0.0.238 70 10.0.0.239 125 10.0.0.240 100 10.0.0.241 175 10.0.0.242 800 10.0.0.243 900 10.0.0.245 4 10.99.99.2 2 Connections to local IP addresses 10.0.0.206 6000 10.0.0.220 6 10.99.99.1 2 Connections to top 10 local ports 3306 6000 48645 1 55920 1 55921 1 55922 1 55923 1 60125 50 60126 125 7789 1 783 1 States of connections ESTABLISHED 300 FIN_WAIT2 15 LISTEN 15 TIME_WAIT 6000 # Top Processes ############################################## PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 19531 sql 20 0 31.4g 23g 15m S 938 74.4 3944:05 mysqld 18878 redis 20 0 521m 516m 504 S 5 1.6 35:55.58 redis-server 18770 redis 20 0 2943m 2.6g 492 S 4 8.4 30:24.52 redis-server 2346 root 20 0 0 0 0 S 2 0.0 19576:16 drbd_r_r0 2354 root 20 0 0 0 0 S 2 0.0 5083:31 drbd_a_r0 29371 root 39 19 0 0 0 S 2 0.0 596:40.50 kipmi0 1 root 20 0 4300 336 332 S 0 0.0 1:25.06 init 2 root 20 0 0 0 0 S 0 0.0 0:01.13 kthreadd 3 root 20 0 0 0 0 S 0 0.0 227:06.71 ksoftirqd/0 # Notable Processes ########################################## PID OOM COMMAND 2324 -17 sshd 18389 -17 udevd # The End ####################################################