/tmp not full but PHP can not create sessions

[luijk]

Earlier today all my sites started returning 500 errors intermittently. Over the last 20 hours a remote testing service that checks every 5 minutes has returned a 500 error at a rate of 15%.

In the error logs it says:

[26-Dec-2009 01:45:06] PHP Warning: session_start() [<a href='function.session-start'>function.session-start</a>]: open(/tmp/sess_99ba9842d34c<masked>, O_RDWR) failed: No space left on device (28) in /home/<masked>/public_html/manager/includes/config.inc.php on line 140

The hosting company says that /tmp is no where near full and that it is a problem with the script. So I created a test script as simple as

<?php
session_start();
?>

This also generates the same errors, again intermittently.

The hosting company is insisting that there is nothing wrong with the server as all there lights are green. Does anyone know what could be the matter?

[thewebhostingdi]

Please make sure that the permission to the /tmp folder is appropriately set by contacting your server admin.

[madaboutlinux]

The error "No space left on device" may occur because of semaphores as well. Kill the active semaphore proecss and try again.

If there isn't a permission problem OR the semaphore problem as specified above, have someone look into your issue.

[luijk]

Thanks for your reply.

This is an intermittent problem, i.e. most of the time it works. So unless the permissions are being changed often I can't see it being a permission problem.

[luijk]

madaboutlinux: Didn't see your reply there. Semaphores does sound like a possible suspect. I will have to convince the host there is a problem first before they will start killing processes.