Data are chunked and dispersed on multiple nodes. There is a kind of "parity" data allowing to lost one or mode nodes ("like" RAID5 or RAID6).
- good capacity (perfect for HDD storage)
- simple to setup
- simple to maintain
- various level of protection
- not all configrations possible (3, 5, 6 nodes and more)
- limited performances on SSDs (replication is better in this case)
This is similar to RAID5: there is an algorithm that will generate a kind of parity, being able to continue to work even if 1 node is down. If you reintroduce the node, it will be "healed" automatically.
If you lose one node, your data are still here. This mode will give you 66% of your total disk space.
Same than 3, like RAID5, you can lose 1 node without service interruption.
In this case, you'll be able to use up to 80% of your total storage capacity!
It's very similar to RAID6. You can lose up to 2 nodes, it will continue to work in read and write.
You can grow a replicated XOSAN by adding extra disperse volumes, in other words a new disperse will be like in RAID 0 with the old one. It's a distributed-disperse type. Some examples:
- To grow a disperse 3, you need 3 new nodes. You'll add the total capacity of each disperse to make a distributed-disperse on 2x3 dispersed nodes.
- To grow a disperse 6, you need 6 new nodes.