The item vfs.file.contents is limited to 64K and so as the text field for MySQL engine.

Sometimes it's required to pick up bigger content from /proc/diskstats to pass this information to the preprocessor for example in "Template Module Linux block devices by Zabbix agent active"

The limitation is currently installed at the agent side. Please:

1) Increase the limit of item key 'vfs.file.contents' or 

2) Allow an override or

3) Invent a different agent key 

Currently to workaround issue must alter template "Template Module Linux block devices by Zabbix agent active" and use:

system.run["cat /proc/diskstats"]

which is not suitable for some environments.