PHP and MySQL settings

iTop is capable of uploading and storing documents (i.e files) as attachments to various objects (Tickets, CIs…). These documents are stored as binary blobs in the iTop database. In order to to safely upload and store documents, several settings must be adjusted consistently across PHP and MySQL.

In PHP, several variables govern the upload of files:

file_uploads	Set to 1 to allow file upload, to zero to prevent all file uploads.
upload_tmp_dir	The temporary location (on the server) were the uploaded files will be stored. Make sure that this parameter points to a location that is accessible (and writable) by the process running the web server (or by the end users in case of IIS with the Windows built-in authentication) and that there is enough space left.
upload_max_filesize	The maximum size allowed for an uploaded file. The value is expressed in bytes. You can use units like K for kilobytes (=1024 bytes), M for megabytes and G for gigabytes. Example: 4M stands for 4 megabytes.
max_file_uploads	The maximum number of files that can be uploaded simultaneously in a single web page. iTop should normally upload only one file at a time. You can safely use the default value, which is 20.
post_max_size	The maximum amount of data that can be sent to the server via a POST request. This value MUST BE bigger than upload_max_filesize, since the same request will contain some more information (the title of the document, an operation code…). So it’s better to put a bigger value here. For example, if upload_max_filesize is 4M, then put 5M for post_max_size.
memory_limit	After being uploaded on the server, the file will be read in memory before being stored in the database. Therefore make sure that memory_limit (if enabled) is far bigger than upload_max_filesize.
max_input_time	This value defines the maximum time allowed for the server to read its input. This includes the time spent uploading the files. The default of 60 seconds may be exceeded for uploading big files over slow connections.

The uploaded files are stored into the MySQL database, each file in one query. Therefore the maximum size allowed for a query MUST BE BIGGER than the maximum size of the uploaded file. This is configured via the variable max_allowed_packet in the my.cnf configuration file (on the MySQL server).

It is good practice to have the following relation between the various settings:

upload_max_filesize	<	post_max_size	<	max_allowed_packet	<	memory_limit
php.ini		php.ini		my.cnf		php.ini

If you ever have an issue linked with mysqldump, there is another parameter max_allowed_packet you can act on, in the same file my.cnf but under [mysqldump] section

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PHP and MySQL settings