autovacuum question

  Hello,

I had a problem in my computer system yesterday. Some data has
disappeared. I was looking for a program that might have deleted it
accidentally. Before I found anything, the data suddenly came back. I
thought it must be a transaction id wraparound problem.

The system is running on FreeBSD 6.2. Postgresql version is 8.1.8 and it
was installed from FreeBSD's standard ports tree. It also installed a
script that vacuums all databases daily. This script was turned on, and
I got emails every day, telling me that the databases were vacuumed.
However, when I opened some tables from within pgadmin3, I got the
message "pg_autovacuum recommened".

Summary: I'm vacuuming all databases daily, but probably I had a
transaction wraparound.

I thought I should enable autovacuum. I read the docs and did the following:

1. Changed postgresql.conf:

stats_start_collector = on
stats_row_level = on
autovacuum = on

2. Restarted the postgresql service.

Now, I do not see a "separate autovacuum daemon" running. What did I
wrong? Here are my tips:

a.) atovacuum daemon is part of the "postgres" process, so I won't see
it running in the process list (how can I check if it is working?)
b.) there is a separate program that I should start (where?)
c.) I missed some extra configuration (what should I do?)
d.) something else

Please help me out.
Thanks,

   Laszlo