It's a very different architecture and design. You can head to https://logdevice.io/docs/Concepts.html to learn more about how LogDevice works.
In terms of function. LogDevice is similar to the core of Apache Kafka.
In terms of function. LogDevice is similar to the core of Apache Kafka.
- There is no many-to-many log recovery whereas -- for example in Pulsar/DistributedLog -- logs are stored in small segments and distributed to multiple nodes.
- Read scalability. Since all the log is stored in one node (with some replicas) the readers are bound to single disk sequential read capacity. Again Pulsar stores logs in segments that are distributed among broker nodes which helps a lot when there are many readers.
All of this is done while preserving the total ordering guarantee thanks the separation of sequencing and storage.
The operator could for example set a bigger node set size for logs that are known to have multiple consumers and require more IO capacity.
At facebook, we have use cases where a single consumer will need to replay a backlog of records in a log, sometimes hours or days worth of data to rebuild its state. We call this a backfill. Node sets allow the IO to be spread across multiple disks which improves backfill speed and helps reduce hotspots.
-- Adrien from the LogDevice team.
Curious where logdevice would be a bad decision..