openstack/swift
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Update ring overview for reuse of device ids

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Change-Id: Ied15706d4cc931b5314001a02457f83e175c5d24
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Paul Dardeau 2016-03-17 22:12:42 +00:00
parent 902cb8f8d7
commit a85149c40e
1 changed files with 8 additions and 4 deletions
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doc/source/overview_ring.rst
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@ -103,10 +103,14 @@ meta string A general-use field for storing additional information for the
====== ======= ==============================================================
Note: The list of devices may contain holes, or indexes set to None, for
devices that have been removed from the cluster. Generally, device ids are not
reused. Also, some devices may be temporarily disabled by setting their weight
to 0.0. To obtain a list of active devices (for uptime polling, for example)
the Python code would look like: ``devices = list(self._iter_devs())``
devices that have been removed from the cluster. However, device ids are
reused. Device ids are reused to avoid potentially running out of device id
slots when there are available slots (from prior removal of devices). A
consequence of this device id reuse is that the device id (integer value) does
not necessarily correspond with the chronology of when the device was added to
the ring. Also, some devices may be temporarily disabled by setting their
weight to 0.0. To obtain a list of active devices (for uptime polling, for
example) the Python code would look like: ``devices = list(self._iter_devs())``
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Partition Assignment List