SQL error

Error 1, 'Can't create/write to file '/var/tmp/#sql_721_0.MAI' (Errcode: 28)'

at /var/www/trinova/data/www/trinova-shop.ru/inc/db_sql.php:43

Query: SELECT id, portfolio_id, name, info, file FROM response WHERE portfolio_id<>0 AND published=1 ORDER BY RAND()