Our moblab received a new update 9901.76.0, after auto-update to 9901.76.0, we run CTS_N test suite, and we found all x86 test package of CTS_N test suite encountered test error. (Unhandled IOError: [Errno 5] Input/output error)

To fixed this problem, we reset our moblab and format our external hard disk. The symptom disappeared.
Is it required to reset Moblab after auto update?
Thank you.

CpCon link to errors:
https://www.google.com/chromeos/partner/console/a/67/testSuiteDetails?board=sand&chromeOsVersion=10032.61.0&suite=cts_n


From the logs here :

12/06 13:31:04.620 INFO |        server_job:0214| 	ERROR	cheets_CTS_N.CtsAadbHostTestCases	cheets_CTS_N.CtsAadbHostTestCases	timestamp=1512595864	localtime=Dec 06 13:31:04	Unhandled IOError: [Errno 5] Input/output error
  Traceback (most recent call last):
    File "/usr/local/autotest/client/common_lib/test.py", line 573, in _exec
      _cherry_pick_call(self.initialize, *args, **dargs)
    File "/usr/local/autotest/client/common_lib/test.py", line 721, in _cherry_pick_call
      return func(*p_args, **p_dargs)
    File "/usr/local/autotest/server/cros/tradefed_test.py", line 465, in initialize
      uri or self._get_default_bundle_url(bundle))
    File "/usr/local/autotest/server/cros/tradefed_test.py", line 759, in _install_bundle
      local = self._instance_copy(cache_path)
    File "/usr/local/autotest/server/cros/tradefed_test.py", line 749, in _instance_copy
      shutil.copyfile(cache_path, instance_path)
    File "/usr/lib/python2.7/shutil.py", line 84, in copyfile
      copyfileobj(fsrc, fdst)
    File "/usr/lib/python2.7/shutil.py", line 49, in copyfileobj
      buf = fsrc.read(length)
  IOError: [Errno 5] Input/output error
12/06 13:31:04.620 INFO |        server_job:0214| END ERROR	cheets_CTS_N.CtsAadbHostTestCases	cheets_CTS_N.CtsAadbHostTestCases	timestamp=1512595864	localtime=Dec 06 13:31:04	
12/06 13:31:04.621 INFO |        server_job:0857| Finished processing control file
12/06 13:31:04.622 ERROR|   logging_manager:0626| tko parser: {'builds': "{'cros-version': 'sand-release/R63-10032.61.0'}", 'job_started': 1512595786, 'hostname': '192.168.231.108', 'status_version': 1, 'label': 'sand-release/R63-10032.61.0/cts_N/cheets_CTS_N.x86.CtsAadbHostTestCases', 'parent_job_id': 1343, 'build': 'sand-release/R63-10032.61.0', 'drone': 'localhost', 'user': 'moblab', 'suite': 'cts_N', 'experimental': 'False', 'job_queued': 1512540291}