CODEWITHSUNDEEP
javacluster-computinghazelcast
huican
huican

Reputation: 505

hazelcast in-memory map lost data when some nodes suddenly died

hazelcast in-memory map lost data when some nodes suddenly died.

For example, in a 3-node cluster, we have a shared map, considering the map has 3 entries (A,B,C), with default backup=1, those 3 entries equaly distributed to nodes, for example it could be:

Entry A: node 1, node 2
Entry B: node 2, node 3
Entry C: node 1, node 3.

When the node2 and node3 suddenly died at the same time before the node1 can finish repartition, then the entry B lost forever.

Any idea to overcome this problem:

  1. We tried to change the map backup count from 1 to 3, it worked for above 3-node case, but the problem still could exist at higher number cluster in some case.
  2. Is there any way to force this map backup on every node, e.g, set the backup-count to node number?
  3. We don't persistent the data to storage.

Upvotes: 2

Views: 2181

Answers (2)

pveentjer
pveentjer

Reputation: 11307

In Hazelcast 3 you can configure the number of synchronous and asynchronous backups.

But if you want to have high availability, you need to have add more machines; the more you add, the higher the availability will be.

We have functionality for offloading to a database for example using the MapStore and MapLoader interface. We do not have (yet) out of the box persistence to disk.

Upvotes: 2

Praba
Praba

Reputation: 1381

As of 2.1, their Distributed Queue supported custom backup counts and the Queues are backed up by distributed maps. Not sure if it's still supported in the latest version. Please take a look here: http://www.hazelcast.com/docs/2.1/manual/single_html/#Queue

Upvotes: 0

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