(mysql.info) communication-errors

 
 A.2.10 Communication Errors and Aborted Connections
 ---------------------------------------------------
 
 The server error log can be a useful source of information about
 connection problems. See  error-log. If you start the server
 with the -log-warnings option, you might find messages like this in
 your error log:
 
      010301 14:38:23  Aborted connection 854 to db: 'users' user: 'josh'
 
 If `Aborted connections' messages appear in the error log, the cause
 can be any of the following:
 
    * The client program did not call `mysql_close()' before exiting.
 
    * The client had been sleeping more than `wait_timeout' or
      `interactive_timeout' seconds without issuing any requests to the
      server. See  server-system-variables.
 
    * The client program ended abruptly in the middle of a data transfer.
 
 When any of these things happen, the server increments the
 `Aborted_clients' status variable.
 
 The server increments the `Aborted_connects' status variable when the
 following things happen:
 
    * A client doesn't have privileges to connect to a database.
 
    * A client uses an incorrect password.
 
    * A connection packet doesn't contain the right information.
 
    * It takes more than `connect_timeout' seconds to get a connect
      packet. See  server-system-variables.
 
 If these kinds of things happen, it might indicate that someone is
 trying to break into your server!
 
 Other reasons for problems with aborted clients or aborted connections:
 
    * Use of Ethernet protocol with Linux, both half and full duplex.
      Many Linux Ethernet drivers have this bug. You should test for
      this bug by transferring a huge file via FTP between the client
      and server machines. If a transfer goes in burst-pause-burst-pause
      mode, you are experiencing a Linux duplex syndrome. The only
      solution is switching the duplex mode for both your network card
      and hub/switch to either full duplex or to half duplex and testing
      the results to determine the best setting.
 
    * Some problem with the thread library that causes interrupts on
      reads.
 
    * Badly configured TCP/IP.
 
    * Faulty Ethernets, hubs, switches, cables, and so forth. This can
      be diagnosed properly only by replacing hardware.
 
    * The `max_allowed_packet' variable value is too small or queries
      require more memory than you have allocated for `mysqld'. See
       packet-too-large.
 
 See also  gone-away.
Info Catalog
(mysql.info) packet-too-large
(mysql.info) common-errors
(mysql.info) full-table
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