MySQL Will Not Start¶

MySQL refuses to start, so InteLIS cannot open and nothing can be backed up.

Open a terminal on the InteLIS machine and run the database doctor:
```
sudo intelis fix-database
```
If intelis is not recognised, or fix-database does not exist

The install is older. Run the same tool straight from the internet:
```
sudo bash -c "$(wget -qO- https://raw.githubusercontent.com/deforay/intelis/master/scripts/mysql-doctor.sh)"
```
Type it exactly as shown. Piping the download into bash instead feeds the script its own text as the answers to its questions.
Answer its questions. It asks before each repair, and starts MySQL again after a repair.
Wait for The database is running again. If MySQL was already running, the doctor reports what it fixed instead.

If it reports It still will not start.

The doctor puts mysql-report.txt on the Desktop, or in the home folder when there is no Desktop. Send that file when asking for help. It holds the service log, the database error log, memory, disk and settings. Passwords are removed from it.

Do not reinstall or reformat the machine

The data is almost always intact. A reinstall is the one step that can turn a fixable fault into lost data.

Causes the doctor checks¶

The doctor checks each cause below. Open one to repair it by hand.

The disk is full

df -h / shows less than 500 MB free. MySQL stops when it cannot write. The doctor offers to trim the system logs itself. It also reports a disk that has space left but no room for more files: df -i / shows 95% or more.

Trim the system logs:
```
sudo journalctl --vacuum-size=100M
```
Start MySQL:
```
sudo systemctl start mysql
```

Old database backups in /var/www/intelis/backups/db are usually the largest files on the disk. They end in .sql.zst.gpg, .sql.zst or .sql.gz. Copy them to a USB drive before deleting any, and keep the newest one on the machine.

The machine ran out of memory

The system stopped MySQL to free memory. sudo journalctl -k mentions Out of memory or oom-kill. The doctor also checks innodb_buffer_pool_size. If it is set above 70% of the machine's memory, the doctor offers to switch that setting off, which returns MySQL to its default size.

Close other programs, then start MySQL:

sudo systemctl start mysql

If it happens again, the machine needs more memory.

A configuration file was edited

MySQL rejects a setting in a file under /etc/mysql. The doctor quotes the rejected line. If an earlier working copy of the configuration exists, the doctor offers to put it back. Otherwise, undo the edit by hand, then start MySQL:

sudo systemctl start mysql

The data folder has the wrong owner

This usually follows a copy or a restore run as the administrator. MySQL cannot open files it does not own. ls -ld /var/lib/mysql shows an owner other than mysql.

Give the files back to MySQL:

sudo chown -R mysql:mysql /var/lib/mysql

Start MySQL:
```
sudo systemctl start mysql
```

The data files are damaged

This usually follows a power cut or an unclean shutdown. The error log mentions corruption, a checksum or InnoDB recovery. The doctor does not repair this, because the wrong setting makes the damage permanent.

Send mysql-report.txt and ask for help. Do not change innodb_force_recovery. If /var/www/intelis/backups/db holds a recent backup, restoring it is usually faster and safer than repairing the files. See Restoring from a backup.

The doctor also checks for a blocked MySQL service, a missing connection folder, settings placed under the wrong heading in a MySQL configuration file (the doctor switches them off), another program on the MySQL port, and a wrong database password saved in InteLIS.

Last resort: copy the disk¶

If MySQL cannot be started at all, the data can still be recovered on another machine. Shut the machine down and copy these folders off its disk:

/var/lib/mysql (the database files)
/etc/mysql (the MySQL settings)
/var/www/intelis (the InteLIS installation)

Take the copy before anyone reinstalls the operating system.