Bug 1263724

+++ This bug was initially created as a clone of Bug #1262408 +++

Description of problem:
=========================
When we have many files, say about 5000 files in hot tier, and when detach tier is issued, we can see many files as failed in detach tier status, in this case about 2000 files. But all files are migrated, if we check the backend bricks.

So, is this spurious errors or a serious miss?



[root@zod glusterfs]# gluster v detach-tier vol100 status
                                    Node Rebalanced-files          size       scanned      failures       skipped               status   run time in secs
                               ---------      -----------   -----------   -----------   -----------   -----------         ------------     --------------
                               localhost                0        0Bytes             0             0             0          in progress               0.00
                                  yarrow                0        0Bytes             0             0             0          in progress               0.00
[root@zod glusterfs]# gluster v detach-tier vol100 status
                                    Node Rebalanced-files          size       scanned      failures       skipped               status   run time in secs
                               ---------      -----------   -----------   -----------   -----------   -----------         ------------     --------------
                               localhost             1157         2.5GB          4736          1814             0            completed              98.00
                                  yarrow             1897       526.1MB          3056          1156             0            completed              97.00

Version-Release number of selected component (if applicable):
================================================================
[root@zod ~]# rpm -qa|grep gluster
glusterfs-client-xlators-3.7.4-0.27.git143f0f9.el7.centos.x86_64
glusterfs-cli-3.7.4-0.27.git143f0f9.el7.centos.x86_64
glusterfs-libs-3.7.4-0.27.git143f0f9.el7.centos.x86_64
glusterfs-api-3.7.4-0.27.git143f0f9.el7.centos.x86_64
glusterfs-fuse-3.7.4-0.27.git143f0f9.el7.centos.x86_64
glusterfs-debuginfo-3.7.4-0.27.git143f0f9.el7.centos.x86_64
glusterfs-server-3.7.4-0.27.git143f0f9.el7.centos.x86_64
glusterfs-3.7.4-0.27.git143f0f9.el7.centos.x86_64
[root@zod ~]# gluster --version
glusterfs 3.7.4 built on Sep  9 2015 01:30:47
Repository revision: git://git.gluster.com/glusterfs.git
Copyright (c) 2006-2011 Gluster Inc. <http://www.gluster.com>
GlusterFS comes with ABSOLUTELY NO WARRANTY.
You may redistribute copies of GlusterFS under the terms of the GNU General Public License.
[root@zod ~]# 



Steps to Reproduce:
==================
1.have a tier volume and create thousands of files such that they are in hot tier
2.now issue a detach tier start and wait for it to complete
3.now check the detach tier status, which will show as complete for each node.
But it can also be seen many failures

[root@zod glusterfs]# gluster v detach-tier vol100 status
                                    Node Rebalanced-files          size       scanned      failures       skipped               status   run time in secs
                               ---------      -----------   -----------   -----------   -----------   -----------         ------------     --------------
                               localhost                0        0Bytes             0             0             0          in progress               0.00
                                  yarrow                0        0Bytes             0             0             0          in progress               0.00
[root@zod glusterfs]# gluster v detach-tier vol100 status
                                    Node Rebalanced-files          size       scanned      failures       skipped               status   run time in secs
                               ---------      -----------   -----------   -----------   -----------   -----------         ------------     --------------
                               localhost             1157         2.5GB          4736          1814             0            completed              98.00
                                  yarrow             1897       526.1MB          3056          1156             0            completed              97.00