Creating an rpm repository using 'createrepo' on an RHS volume results in taking a long time to finish, why?

Issue

• Creating an rpm repository using 'createrepo' on an RHS volume results in taking a long time to finish, why?

• Running 'createrepo' on a directory containing rpm package shipped with RHEL takes more than 14 hours to finish. The rpms are in a directory on a GlusterFS volume.

• The same operation will finish within 3 minutes on a local file systems.

#sudo createrepo -d --update --skip-stat .
13093/13093 - wget-1.12-1.12.el6_5.x86_64.rpm                                   
Saving Primary metadata
Saving file lists metadata
Saving other metadata
Generating sqlite DBs

• All the time spent waiting is spent in building the sqlite databases, and there is a large amount of lseek() followed by read() or write() to the DB files.

• On a local file system :

# time sudo createrepo -d --update --skip-stat .
13093/13093 - java-1.7.0-openjdk-devel-1.7.0.51-2.4.4.1.el6_5.x86_64.rpm
Saving Primary metadata
Saving file lists metadata
Saving other metadata
Generating sqlite DBs
Sqlite DBs complete

real    2m20.958s
user    2m12.991s
sys     0m7.877s