Tonight I found that our Plesk server had got itself into a state where Domains could not be Activated/Suspended, and websites with Databases were not loading correctly (eg WordPress sites etc), errors were as follows :

Website Logs:

WordPress database error Got error 28 from storage engine for query…

Plesk Control Panel Error:

Unable to activate/deactivate domain: Domain Mgmt backend failed: domainmng: /usr/local/psa/admin/bin/ftpmng execution failed:

Looking at the file system (see below), the TMP directory was full so MySQL will have been unable to create any temp tables etc.

df -h
Filesystem            Size  Used Avail Use% Mounted on

/dev/md1         9.2G  354M  8.4G   4% /
/dev/md5         9.4G  1.7G  7.7G  18% /usr
/dev/md6         213G   15G  199G   7% /var
none             990M  988M  1.8M 100% /tmp
tmpfs            990M     0  990M   0% /usr/local/psa/handlers/before-local
tmpfs            990M     0  990M   0% /usr/local/psa/handlers/before-queue
tmpfs            990M     0  990M   0% /usr/local/psa/handlers/before-remote
tmpfs            990M  5.1M  985M   1% /usr/local/psa/handlers/info
tmpfs            990M     0  990M   0% /usr/local/psa/handlers/spool

In my case, TMP was running at 100% and was filled by file : “repo_transport_tmp_HcQKVt” The temp file was a server backup file which was being downloaded to the local repository. After removing the file, ran the following command to restart MySQL

/etc/rc.d/init.d/mysqld restart