Lustre discuss - Jun 2009 - understanding 'lctl dl' output

Hi,

I would like to get better understanding of ''lctl dl'' output.
The output
lists device number, name, UUID, and number of references on the device.
Below is an example of ''lctl dl'' on my test box.
  0 UP mgs MGS MGS 7
  1 UP mgc MGC10.0.0.42 at tcp b165396e-e166-a036-165e-a99c488747a2 5
  2 UP mdt MDS MDS_uuid 3
  3 UP lov lustre-mdtlov lustre-mdtlov_UUID 4
  4 UP mds lustre-MDT0000 lustre-MDT0000_UUID 4
  5 UP osc lustre-OST0000-osc lustre-mdtlov_UUID 5
  6 UP osc lustre-OST0001-osc lustre-mdtlov_UUID 5
  7 UP osc lustre-OST0002-osc lustre-mdtlov_UUID 5
  8 UP osc lustre-OST0003-osc lustre-mdtlov_UUID 5
  9 UP osc lustre-OST0004-osc lustre-mdtlov_UUID 5
 10 UP ost OSS OSS_uuid 3
 11 UP obdfilter lustre-OST0000 lustre-OST0000_UUID 3

- I have observed second column output as ''IN''. Does it mean
inactive?
Are there any other values that it can take?
- What does the number of references on a device indicate?
- Is there any difference in running ''lctl dl'' on MDS, MGS,
combined
MDS/MGS, and client?

Thanks,
Shantanu Pavgi.