openstack/swift
Code Issues Proposed changes

Adjust replica count before pulling parts from failed devices

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When your device count falls below your replica count you can either add
devices or reduce the replica count.

Trying to reduce your replica count fails about half the time because
removing parts from from failed devices temporarily invalidates your
_replica2part2dev table with NONE_DEV which can result in an IndexError
in _adjust_replica2part2dev_size.

If you adjust the replica count first you won't have to worry about
tracking unassigned parts from failed devices.

Closes-Bug: #1558751

Change-Id: I99dc776fd260a2ba68ca77d7b5ed5120d10b06de
This commit is contained in:
Clay Gerrard 2016-03-17 11:55:14 -07:00 committed by Samuel Merritt
parent 3a20e9b246
commit c70abba529
2 changed files with 17 additions and 2 deletions
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4
swift/common/ring/builder.py
View File

@ -443,10 +443,10 @@ class RingBuilder(object):
self._set_parts_wanted(replica_plan)
assign_parts = defaultdict(list)
# gather parts from failed devices
removed_devs = self._gather_parts_from_failed_devices(assign_parts)
# gather parts from replica count adjustment
self._adjust_replica2part2dev_size(assign_parts)
# gather parts from failed devices
removed_devs = self._gather_parts_from_failed_devices(assign_parts)
# gather parts for dispersion (N.B. this only picks up parts that
# *must* disperse according to the replica plan)
self._gather_parts_for_dispersion(assign_parts, replica_plan)

15
test/unit/common/ring/test_builder.py
View File

@ -1385,6 +1385,21 @@ class TestRingBuilder(unittest.TestCase):
rb.rebalance() # this would crash since parts_wanted was not set
rb.validate()
def test_reduce_replicas_after_remove_device(self):
rb = ring.RingBuilder(8, 3, 1)
rb.add_dev({'id': 0, 'region': 0, 'zone': 0, 'weight': 3,
'ip': '127.0.0.1', 'port': 10000, 'device': 'sda'})
rb.add_dev({'id': 1, 'region': 0, 'zone': 0, 'weight': 3,
'ip': '127.0.0.1', 'port': 10000, 'device': 'sda'})
rb.add_dev({'id': 2, 'region': 0, 'zone': 0, 'weight': 3,
'ip': '127.0.0.1', 'port': 10000, 'device': 'sda'})
rb.rebalance()
rb.remove_dev(0)
self.assertRaises(exceptions.RingValidationError, rb.rebalance)
rb.set_replicas(2)
rb.rebalance()
rb.validate()
def test_rebalance_post_upgrade(self):
rb = ring.RingBuilder(8, 3, 1)
# 5 devices: 5 is the smallest number that does not divide 3 * 2^8,