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Architecture - Interoperability 1.6 1.8 2.0

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Note: The content on this page reflects the state of design of a Lustre feature at a particular point in time and may contain outdated information.

Definitions

1.6 current b1_6 branch
1.6-fid b1_6 branch with client support for b_new_cmd wire format. No cmd.
1.8 current b_new_cmd code without clustered metadata functionality, with features to transition from 1.6 to cmd storage.
1.8 limited mode A 1.8 server mounted in limited mode is able to run on top of 1.6 storage, and interoperates with 1.6-fid clients.
1.8 full mode Full mode is achieved through a mount option. It uses 1.8 b_new_cmd code. Server can handle mixed 1.6 and 1.8 storage and makes format changes to the file system that are not compatible with 1.8. No clustered metadata. No interoperability with 1.6 clients.
format upgrade a background script that runs while a 1.8 server is running and upgrades all directory formats to cmd3 format.
2.0 cmd3 code with full interoperability with 1.8 and clustered metadata features.
limited protocol minor discrepancies for 1.6 client - 1.8 server interaction compared with 1.6 -1.6 and 1.8-1.8 interaction.

b_new_cmd is also referred to as cmd3.

1.6-fid will be relased as 1.6.N for some N.

QAS Summary Table

Id Quality Summary
upgrade-srv Feature A server in a 1.6 cluster is upgraded to 1.8. It can mount a 1.6 file system and start in restricted mode.
restricted-mode-srv Feature An upgraded server continues to mount a server file system in restricted moded until a directive is given.
downgrade-srv Feature A server which only has been started in restricted mode is downgraded to a 1.6 server. The 1.6 server can start if only 1.6 clients are present in the cluster.
client-interop Feature A 1.6 client can interoperate with an upgraded server and 1.8 clients running in restricted mode.
client-upgrade Feature A cluster has upgraded all servers from 1.6 to 1.8. An upgrade of a client from 1.6 to 1.8 succeeds.
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