Problem: On RHEL 6.7, we have sqlite version 3.6.2 which doesnt support WAL journaling mode, as this journaling mode is only available in sqlite 3.7 and above. As a result we cannot have to progreses concurrently accessing sqlite, without running into db locks! Well WAL is also need for performace on CTR side. Solution: This solution is to use CTR db connection for doing queries when WAL mode is absent. i,e tier migrator will send sync_op ipc calls to CTR, which in turn will do the query and create/update the query file suggested by tier migrator. Pending: Well this solution will stop the db locks but the performance is still an issue for CTR. We are developing an in-Memory Transaction Log (iMeTaL) which will help boost the CTR performance by doing in memory udpates on the IO path and later flush the updates to the db in a batch/segment flush. Change-Id: Ie3149643ded159234b5cc6aa6cf93b9022c2f124 BUG: 1240577 Signed-off-by: Joseph Fernandes <josferna@redhat.com> Signed-off-by: Dan Lambright <dlambrig@redhat.com> Signed-off-by: Joseph Fernandes <josferna@redhat.com> Reviewed-on: http://review.gluster.org/12191 Tested-by: Gluster Build System <jenkins@build.gluster.com> Reviewed-by: Luis Pabon <lpabon@redhat.com>