Using Stable/Boron.
When datastore grew to a certain size, I received an OOM from the snapshot operation. After analysis the conclusion was that the snapshot is being serialized to a single byte[] and if the size is bigger than 2G, the code of ByteArrayOutputStream will throw an OOM error:
private static int hugeCapacity(int minCapacity)

{ if (minCapacity < 0) // overflow throw new OutOfMemoryError(); return (minCapacity > MAX_ARRAY_SIZE) ? Integer.MAX_VALUE : MAX_ARRAY_SIZE; }

Log:

Uncaught error from thread [opendaylight-cluster-data-akka.actor.default-dispatcher-54] shutting down JVM since 'akka.jvm-exit-on-fatal-error' is enabled for ActorSystem[opendaylight-cluster-data]
java.lang.OutOfMemoryError
at java.io.ByteArrayOutputStream.hugeCapacity(ByteArrayOutputStream.java:123)
at java.io.ByteArrayOutputStream.grow(ByteArrayOutputStream.java:117)
at java.io.ByteArrayOutputStream.ensureCapacity(ByteArrayOutputStream.java:93)
at java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java:153)
at java.io.DataOutputStream.write(DataOutputStream.java:107)
at java.io.ObjectOutputStream$BlockDataOutputStream.drain(ObjectOutputStream.java:1877)
at java.io.ObjectOutputStream$BlockDataOutputStream.write(ObjectOutputStream.java:1808)
at java.io.DataOutputStream.writeInt(DataOutputStream.java:200)
at java.io.ObjectOutputStream$BlockDataOutputStream.writeInt(ObjectOutputStream.java:1943)
at java.io.ObjectOutputStream.writeInt(ObjectOutputStream.java:797)
at org.opendaylight.controller.cluster.datastore.node.utils.stream.AbstractNormalizedNodeDataOutput.writeInt(AbstractNormalizedNodeDataOutput.java:107)
at org.opendaylight.controller.cluster.datastore.node.utils.stream.NormalizedNodeOutputStreamWriter.writeString(NormalizedNodeOutputStreamWriter.java:60)
at org.opendaylight.controller.cluster.datastore.node.utils.stream.NormalizedNodeOutputStreamWriter.writeQName(NormalizedNodeOutputStreamWriter.java:47)
at org.opendaylight.controller.cluster.datastore.node.utils.stream.AbstractNormalizedNodeDataOutput.writeKeyValueMap(AbstractNormalizedNodeDataOutput.java:400)
at org.opendaylight.controller.cluster.datastore.node.utils.stream.AbstractNormalizedNodeDataOutput.startMapEntryNode(AbstractNormalizedNodeDataOutput.java:250)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter$OrderedNormalizedNodeWriter.writeMapEntryNode(NormalizedNodeWriter.java:267)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessedAsCompositeNode(NormalizedNodeWriter.java:208)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:100)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.writeChildren(NormalizedNodeWriter.java:171)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessedAsCompositeNode(NormalizedNodeWriter.java:238)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:100)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.writeChildren(NormalizedNodeWriter.java:171)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessedAsCompositeNode(NormalizedNodeWriter.java:196)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:100)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.writeChildren(NormalizedNodeWriter.java:171)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter$OrderedNormalizedNodeWriter.writeMapEntryNode(NormalizedNodeWriter.java:282)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessedAsCompositeNode(NormalizedNodeWriter.java:208)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:100)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.writeChildren(NormalizedNodeWriter.java:171)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessedAsCompositeNode(NormalizedNodeWriter.java:238)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:100)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.writeChildren(NormalizedNodeWriter.java:171)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter$OrderedNormalizedNodeWriter.writeMapEntryNode(NormalizedNodeWriter.java:282)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessedAsCompositeNode(NormalizedNodeWriter.java:208)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:100)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.writeChildren(NormalizedNodeWriter.java:171)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessedAsCompositeNode(NormalizedNodeWriter.java:238)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:100)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.writeChildren(NormalizedNodeWriter.java:171)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessedAsCompositeNode(NormalizedNodeWriter.java:223)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:100)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.writeChildren(NormalizedNodeWriter.java:171)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter$OrderedNormalizedNodeWriter.writeMapEntryNode(NormalizedNodeWriter.java:282)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessedAsCompositeNode(NormalizedNodeWriter.java:208)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:100)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.writeChildren(NormalizedNodeWriter.java:171)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessedAsCompositeNode(NormalizedNodeWriter.java:238)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:100)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.writeChildren(NormalizedNodeWriter.java:171)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessedAsCompositeNode(NormalizedNodeWriter.java:196)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:100)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.writeChildren(NormalizedNodeWriter.java:171)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessedAsCompositeNode(NormalizedNodeWriter.java:196)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:100)
at org.opendaylight.controller.cluster.datastore.node.utils.stream.AbstractNormalizedNodeDataOutput.writeNormalizedNode(AbstractNormalizedNodeDataOutput.java:157)
at org.opendaylight.controller.cluster.datastore.utils.SerializationUtils.serializeNormalizedNode(SerializationUtils.java:90)
at org.opendaylight.controller.cluster.datastore.persisted.MetadataShardDataTreeSnapshot$Proxy.writeExternal(MetadataShardDataTreeSnapshot.java:56)
at java.io.ObjectOutputStream.writeExternalData(ObjectOutputStream.java:1459)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1430)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
at org.opendaylight.controller.cluster.datastore.persisted.AbstractVersionedShardDataTreeSnapshot.versionedSerialize(AbstractVersionedShardDataTreeSnapshot.java:77)
at org.opendaylight.controller.cluster.datastore.persisted.AbstractVersionedShardDataTreeSnapshot.serialize(AbstractVersionedShardDataTreeSnapshot.java:95)
at org.opendaylight.controller.cluster.datastore.actors.ShardSnapshotActor.handleReceive(ShardSnapshotActor.java:54)
at org.opendaylight.controller.cluster.common.actor.AbstractUntypedActor.onReceive(AbstractUntypedActor.java:26)
at org.opendaylight.controller.cluster.common.actor.MeteringBehavior.apply(MeteringBehavior.java:97)
at akka.actor.ActorCell$$anonfun$become$1.applyOrElse(ActorCell.scala:544)
at akka.actor.Actor$class.aroundReceive(Actor.scala:484)
at akka.actor.UntypedActor.aroundReceive(UntypedActor.scala:95)
at akka.actor.ActorCell.receiveMessage(ActorCell.scala:526)
at akka.actor.ActorCell.invoke(ActorCell.scala:495)
at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:257)
at akka.dispatch.Mailbox.run(Mailbox.scala:224)
at akka.dispatch.Mailbox.exec(Mailbox.scala:234)
at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)
at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)
Suppressed: java.lang.OutOfMemoryError