If the scratch partition (/tmp) gets filled up, check for the presence of the file ql_ima.log. If it is present, you are bothered by a bug from an older version of the qla4xxx driver. Even if you use Update Manager, this driver does not get updated automatically. The solution is add the driver to Update Manager or download and install the update manually.
This procedure describes the manual installation of the update on your ESX host. There's no need to put the host in maintenance mode but you will have to reboot to use the new driver.
Download the driver (you need a VMware account):
Unpack the download and copy the file qla4xxx-618.104.22.168-offline_bundle-1682448.zip to a VMware datastore.
Using VMware CLI (via SSH, the console or a management server/appliance), update the driver:
esxcli software vib update -d /vmfs/volumes/datastore-name/qla4xxx-622.214.171.124-offline_bundle-1682448.zip
The update takes some time, and afterwards, you need to reboot the host.