Cannot start MongoDB: System error 1067 in Windows

[gregorinator]

We're running MongoDB 2.2 as a service under Windows 2008, 64 bit.
With journaling enabled. We had a master/slave setup, but wanted to
convert to a replica set . Perhaps naively, I assumed it was as easy
as this: I stopped the Windows service, removed the line "master =
true" from the config file, added this line:

replSet = tdms2_rs

and tried to start the Windows service again. I got this error:

A system error has occurred.

System error 1067 has occurred.

The process terminated unexpectedly.

I quickly put the config file back the way it was, but it made no
difference. Every time I try to start the service, I get this error.
Mongo is now down.

I'm desperate. What can I try?

gs

[gregorinator]

>      System error 1067 has occurred.

I took a couple deep breaths and it occurred to me to do what I guess
was obvious: Run mongod.exe from the command line, instead of trying
to start it as a service. That displayed the actual MongoDB error
messages, and it turned out that there wasn't enough free space to
preallocate the journal file. It was as simple as that. One that was
resolved, the Windows service started up like a charm.

Then I checked the log file, and sure enough, the messages were there,
too. So it wasn't an issue with the Windows service. It was just
that the service, when it encountered the error, wasn't able to pass
through the actual error messages.

gs