It seems that part of the KegBot database has become corrupted and causes mySQL to crash.
root@kegbot:~# mysqlcheck kegbot core_apikey -f
mysqlcheck: Got error: 2013: Lost connection to MySQL server during query when executing 'CHECK TABLE … ’
From /var/log/syslog:
May 13 13:11:21 kegbot mysqld_safe: Starting mysqld daemon with databases from /var/lib/mysql
May 13 13:11:22 kegbot mysqld: 150513 13:11:22 [Warning] Using unique option prefix key_buffer instead of key_buffer_size is deprecated and will be removed in a future release. Please use the full name instead.
May 13 13:11:22 kegbot mysqld: 150513 13:11:22 [Note] /usr/sbin/mysqld (mysqld 5.5.43-0+deb7u1) starting as process 9619 …
May 13 13:11:22 kegbot mysqld: 150513 13:11:22 [Warning] Using unique option prefix myisam-recover instead of myisam-recover-options is deprecated and will be removed in a future release. Please use the full name instead.
May 13 13:11:22 kegbot mysqld: 150513 13:11:22 [Note] Plugin ‘FEDERATED’ is disabled.
May 13 13:11:22 kegbot mysqld: 150513 13:11:22 InnoDB: The InnoDB memory heap is disabled
May 13 13:11:22 kegbot mysqld: 150513 13:11:22 InnoDB: Mutexes and rw_locks use GCC atomic builtins
May 13 13:11:22 kegbot mysqld: 150513 13:11:22 InnoDB: Compressed tables use zlib 1.2.7
May 13 13:11:22 kegbot mysqld: 150513 13:11:22 InnoDB: Using Linux native AIO
May 13 13:11:23 kegbot mysqld: 150513 13:11:23 InnoDB: Initializing buffer pool, size = 128.0M
May 13 13:11:23 kegbot mysqld: 150513 13:11:23 InnoDB: Completed initialization of buffer pool
May 13 13:11:23 kegbot mysqld: 150513 13:11:23 InnoDB: highest supported file format is Barracuda.
May 13 13:11:24 kegbot mysqld: 150513 13:11:24 InnoDB: Waiting for the background threads to start
May 13 13:11:25 kegbot mysqld: 150513 13:11:25 InnoDB: 5.5.43 started; log sequence number 52491352
May 13 13:11:25 kegbot mysqld: 150513 13:11:25 [Note] Server hostname (bind-address): ‘127.0.0.1’; port: 3306
May 13 13:11:25 kegbot mysqld: 150513 13:11:25 [Note] - ‘127.0.0.1’ resolves to ‘127.0.0.1’;
May 13 13:11:25 kegbot mysqld: 150513 13:11:25 [Note] Server socket created on IP: ‘127.0.0.1’.
May 13 13:11:26 kegbot mysqld: 150513 13:11:26 [Note] Event Scheduler: Loaded 0 events
May 13 13:11:26 kegbot mysqld: 150513 13:11:26 [Note] /usr/sbin/mysqld: ready for connections.
May 13 13:11:26 kegbot mysqld: Version: ‘5.5.43-0+deb7u1’ socket: ‘/var/run/mysqld/mysqld.sock’ port: 3306 (Debian)
May 13 13:11:31 kegbot /etc/mysql/debian-start[9729]: Upgrading MySQL tables if necessary.
May 13 13:11:35 kegbot mysqld: 150513 13:11:35 InnoDB: Error: space id and page n:o stored in the page
May 13 13:11:35 kegbot mysqld: InnoDB: read in are 2451985909:362583370, should be 0:338!
May 13 13:11:35 kegbot mysqld: InnoDB: Database page corruption on disk or a failed
May 13 13:11:35 kegbot mysqld: InnoDB: file read of page 338.
May 13 13:11:35 kegbot mysqld: InnoDB: You may have to recover from a backup.
May 13 13:11:35 kegbot mysqld: 150513 13:11:35 InnoDB: Page dump in ascii and hex (16384 bytes):
||/ Name Version Architecture Description
++±=====================================-=======================================-============-ii libdbd-mysql-perl 4.021-1 armhf Perl5 database interface to the MySQL database
ii libmysqlclient-dev 5.5.43-0+deb7u1 armhf MySQL database development files
ii libmysqlclient16 5.1.62-1 armhf MySQL database client library
ii libmysqlclient18:armhf 5.5.43-0+deb7u1 armhf MySQL database client library
ii libsqlite3-0:armhf 3.7.13-1+deb7u1 armhf SQLite 3 shared library
ii mysql-client-5.5 5.5.43-0+deb7u1 armhf MySQL database client binaries
ii mysql-common 5.5.43-0+deb7u1 all MySQL database common files, e.g. /etc/mysql/my.cnf
ii mysql-server 5.5.43-0+deb7u1 all MySQL database server (metapackage depending on the latest version)
ii mysql-server-5.5 5.5.43-0+deb7u1 armhf MySQL database server binaries and system database setup
ii mysql-server-core-5.5 5.5.43-0+deb7u1 armhf MySQL database server binaries
ii idle-python2.7 2.7.3-6+deb7u2 all IDE for Python (v2.7) using Tkinter
ii idle-python3.2 3.2.3-7 all IDE for Python (v3.2) using Tkinter
ii libpython2.7 2.7.3-6+deb7u2 armhf Shared Python runtime library (version 2.7)
ii python 2.7.3-4+deb7u1 all interactive high-level object-oriented language (default version)
ii python-dbus 1.1.1-1 armhf simple interprocess messaging system (Python interface)
ii python-dbus-dev 1.1.1-1 all main loop integration development files for python-dbus
ii python-dev 2.7.3-4+deb7u1 all header files and a static library for Python (default)
ii python-gi 3.8.2-1+rpi1rpi2 armhf Python 2.x bindings for gobject-introspection libraries
ii python-medusa 1:0.5.4-7 all Framework for implementing asynchronous servers
ii python-meld3 0.6.5-3.1 armhf An HTML/XML templating system for Python
ii python-minimal 2.7.3-4+deb7u1 all minimal subset of the Python language (default version)
ii python-numpy 1:1.6.2-1.2 armhf Numerical Python adds a fast array facility to the Python language
ii python-picamera 1.10-1 armhf Pure Python interface to the Raspberry Pi’s camera module.
ii python-pifacecommon 4.1.2-1 all The PiFace common functions module.
ii python-pifacedigitalio 3.0.4-1 all The PiFace Digital I/O module.
ii python-pkg-resources 0.6.24-1 all Package Discovery and Resource Access using pkg_resources
ii python-pygame 1.9.1release+dfsg-8 armhf SDL bindings for games development in Python
ii python-rpi.gpio 0.5.11-1 armhf Python GPIO module for Raspberry Pi
ii python-serial 2.5-2.1 all pyserial - module encapsulating access for the serial port
ii python-setuptools 0.6.24-1 all Python Distutils Enhancements (setuptools compatibility)
ii python-support 1.0.15 all automated rebuilding support for Python modules
ii python-tk 2.7.3-1 armhf Tkinter - Writing Tk applications with Python
ii python2.7 2.7.3-6+deb7u2 armhf Interactive high-level object-oriented language (version 2.7)
ii python2.7-dev 2.7.3-6+deb7u2 armhf Header files and a static library for Python (v2.7)
ii python2.7-minimal 2.7.3-6+deb7u2 armhf Minimal subset of the Python language (version 2.7)
ii python3 3.2.3-6 all interactive high-level object-oriented language (default python3 version)
ii python3-minimal 3.2.3-6 all minimal subset of the Python language (default python3 version)
ii python3-numpy 1:1.6.2-1.2 armhf Numerical Python adds a fast array facility to the Python language
ii python3-picamera 1.10-1 armhf Pure Python interface to the Raspberry Pi’s camera module.
ii python3-pifacecommon 4.1.2-1 all The PiFace common functions module.
ii python3-pifacedigital-scratch-handler 2.0.5-1 all The PiFace Digital Scratch Handler.
ii python3-pifacedigitalio 3.0.4-1 all The PiFace Digital I/O module.
ii python3-rpi.gpio 0.5.11-1 armhf Python 3 GPIO module for Raspberry Pi
ii python3-serial 2.5-2.1 all pyserial - module encapsulating access for the serial port
ii python3-tk 3.2.3-1 armhf Tkinter - Writing Tk applications with Python 3.x
ii python3.2 3.2.3-7 armhf Interactive high-level object-oriented language (version 3.2)
ii python3.2-minimal 3.2.3-7 armhf Minimal subset of the Python language (version 3.2)
root@kegbot:~# cat /etc/debian_version
7.8
root@kegbot:~# uname -a
Linux kegbot 3.18.11+ #781 PREEMPT Tue Apr 21 18:02:18 BST 2015 armv6l GNU/Linux