Dell Powerscale is a private proprietary distributed storage system and a great example of what enterprise clients might be wanting from SN.
https://www.delltechnologies.com/en-us/storage/powerscale.htm
The site is really interesting from many different marketing perspectives, from the feature list to the visual presentation and the copy. Pretty incredible how close it is to SN in terms of the value proposition for these types of users.
The technical overview is very detailed and again shows what enterprise users will be interested in and also discusses a bit about what is implemented and why those features are there.
The technical overview has a bit of explanation for when to use erasure coding vs mirroring (powerscale supports both types of redundancy, although file metadata is always mirrored), and is kinda interesting in the context of competing networks like storj that use erasure coding for data integrity vs SN using mirroring.
Metadata (which makes up generally less than 1% of the system) is mirrored in the cluster for performance and availability
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OneFS metadata and inodes are always protected by mirroring, rather than Reed-Solomon coding, and with at least the level of protection as the data they reference.
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Mirroring, when applied to user data, tends to be used more for high-transaction performance cases
This is sort of a complex point, in many cases erasure coding will give faster client performance than mirroring, but it’s pretty nice to see some info about the two redundancy techniques presented side-by-side.