'System error 45' - Quota error during update?

[thedevilman]

when updating to plesk to 7.5.4 (from 7.5.3) everything seemed to have gone well but when checking the log i found two errors. both were the same...

System error 45: Operation not supported
Quota is not supported by your operating system.
Probably kernel has not compiled in quota support.

WARNING!
During the check for quota support found some small problems
Continue...

i'm not quite sure what to make of it, can anyone help simplify that for my novice brain. amazingly google didn't help me much on this one.

thX!
-thedevilman