My b2evolution Version: Not Entered

When I hit "direct b-hits" while on the "all" tab, I get:

MySQL error!

Error writing file '/ramdisk/mysql/tmp/MYDh00Vq' (Errcode: 28)(Errno=3)

Your query: Results::Query()

SELECT hit_ID, hit_datetime, hit_blog_ID, hit_uri, hit_remote_addr, blog_shortname

FROM evo_hitlog INNER JOIN evo_useragents ON hit_agnt_ID = agnt_ID
LEFT JOIN evo_blogs ON hit_blog_ID = blog_ID

WHERE hit_referer_type = 'direct'

AND agnt_type = 'browser'

ORDER BY hit_datetime DESC

LIMIT 0, 20

Is that normal? It's not really a big deal, but just wondering.