diff --git a/source/core/sharding-internals.txt b/source/core/sharding-internals.txt index a884bde8140..4edcf78b785 100644 --- a/source/core/sharding-internals.txt +++ b/source/core/sharding-internals.txt @@ -348,10 +348,15 @@ The migration process ensures consistency and maximizes availability of chunks during balancing: when MongoDB begins migrating a chunk, the database begins copying the data to the new server and tracks incoming write operations. After migrating chunks, the "from" :program:`mongod` -sends all new writes, to the "receiving" server. Finally, +sends all new writes to the "receiving" server. Finally, :program:`mongos` updates the chunk record in the :term:`config database` to reflect the new location of the chunk. +.. note:: Before MongoDB version 2.0, increasing clock skew between + :program:`mongos` instances could lead to failed distributed locks + and potential data loss, particularly if the skew exceeded 5 minutes. + Always run ``ntpd`` to minimize clock skew. + .. _sharding-migration-thresholds: Migration Thresholds