fwrite(): Write of 65536 bytes failed.. errno=28 No space left on device.

Ratna

Hi all

When I do > Site administration > Development > Make a test course and select the course size L (1GB), I get:

Creating course L (~1GB; in ~30 min) - done (6.5s) 100%
Creating assignments (500) - done (758.4s) 100%
Creating pages (1000) - done (29.8s) 100%
Creating small files (1024) - done (25.3s) 100%
Creating big files (10) - done (21s) 100%
Notice: fwrite(): Write of 65536 bytes failed with errno=28 No space left on device in /var/www/moodle/admin/tool/generator/classes/course_backend.php on line 510
[tons of repetitions!]
Checking user accounts (10000) - done (0s) 100%
Creating user accounts (10000) - done (355.3s) 100%
Enrolling users into course (10000) - done (230.6s) 100%
Creating forum (5000 posts) - done (47.2s) 100%
Course completed (1474.2s) - done (0s) 100%

Checking the logs, error.log contains:

2025/07/27 17:13:05 [error] 970#970: *368 FastCGI sent in stderr: "; PHP message: PHP Notice: fwrite(): Write of 65536 bytes failed with errno=28 No space left on device in /var/www/moodle/admin/tool/generator/classes/course_backend.php on line 510" while reading upstream, client: 10.0.0.136, server: moodlebox, request: "POST /admin/tool/generator/maketestcourse.php HTTP/1.1", upstream: "fastcgi://unix:/var/run/php/php8.2-fpm.sock:", host: "moodlebox.home", referrer: "http://moodlebox.home/admin/tool/generator/maketestcourse.php"

There is no reason the micro-SD card is a 64 GB one and 'df -h' brings:

/dev/mmcblk0p2 59G 18G 38G 33% /

There is also plenty of resources, this is a Pi 4 8G.

Interestingly though course size M (100MB) runs through (even after this size L failed).

MoodleBox 4.9.0 with Moodle 4.5.5 LTS.

Nicolas

I suspect this is probably the /var/www/moodledata/temp (defaulting to 64 MB) that's full.

Try to increase this in /etc/fstab, reboot and retry to confirm.

Ratna

Nicolas Took a long time to come back (the forum complained).

Yeah, that was it, /var/www/moodledata/temp was too small. After increasing it the process continued.

A hint to those, who expect too much from R Pi: Even with Pi 4 B 8G, generating a course of size L (10 k users) dies. Size M (1 k users) completes.

Ref. https://docs.moodle.org/en/Test_course_generator

Ralf Krause

Hi,
could increasing the temporary memory generally improve the performance of the Moodlebox? Would a Raspberry Pi 4B with 4 or 8 GB of RAM get faster if the RAM were fully utilized? If so, adjusting the temporary memory to the available RAM could be an interesting option. I have no idea what's currently in the temporary memory.
Best regards, Ralf

Ratna

Ralf Krause

Hi, if by "temporary memory" you mean the usual moodledata/temp, a faster "temp" will have a direct impact on any operation which stores data in temp or recall data from there. The impact will not necessarily be "faster" in the sense that a particular operation will finish in a measurably shorter time. The positive effect will show itself when there is a surge of such operations. Then they return roughly in the same time as before the surge which otherwise would have caused a congestion and possibly not return at all! This is one of the tricks Nicolas applied in the MoodleBox to get "unexpected" performance from the Raspberry Pi.

The moodle.org Hardware and performance forum full of such discussions. Its doc pages https://docs.moodle.org/en/Performance and https://docs.moodle.org/en/Performance_FAQ contain summaries.

Nicolas

Ralf Krause could increasing the temporary memory generally improve the performance of the Moodlebox?

Not necessarily. This temp storage is used for storing data during certain operations, such as copying courses, etc. However, the size of it has no impact on the duration of these operations. But the fact that it's stored in RAM, makes it notably faster, as @Ratna says.

Increasing the temp storage would not benefit most of MoodleBox users, IMHO. That's the reason I leave it for advanced users, who know how to edit a file and reboot. Developing a GUI for it would be complex and would also make it more fragile, I suppose.