[Lustre-discuss] Slow du

[Larry Brown]

We have a cluster set up with 60 nodes.  We have a folder with the
striping count set to 20.  We loaded up two folders with a large number
of small files.  I know the bigger the file the better the more Lustre
shines but we have multiple things to test and this is the first.
According to "lfs df -h" there is a total disk use of 76.3G.  I ran "du
-sh" at the top level of the folders and am now at 45 minutes run time
without a result yet.  Top only shows du taking between 3 and 5% cpu
time and 1% of memory.

Does anyone know what causes this?  Shouldn't the server be able to
examine the MDS to sum the space used?  At worst wouldn't the first
object on the stripe return the total file size if it isn't kept on the
MDS?

Larry