Drive
The Drive tab of the System screen. It holds one setting: how large a single file uploaded to Drive may be.
Maximum file size
Maximum file size, MB is a whole number of megabytes greater than zero. The default is 100 MB.
A file larger than the limit is rejected during the upload with a «too large» error, and nothing of it is stored. The limit is per file: it is the size of one file that is measured against it, not the total of everything sent.
Drive files lie on this server's own disk, so the limit can be raised as far as the free space there allows. How much space is left is shown on the Update tab, in the Disk free line.
Press Save to store the new value. The form answers No changes when nothing was changed, and refuses a value that is not a positive whole number. The limit applies to the very next upload — no restart is needed.
Raising or lowering it changes nothing about the files already in Drive: they stay where they are and open as before. Only new uploads are measured against it.