Ceph

h1. Add new feature - Write Once Read Many volume

h3. Summary

This feature will enable user to create a WORM (write once, read many) volume via librbd or rbd cli.

h3. Owners

* Haomai Wang (UnitedStack)

* Name (Affiliation)

* Name

h3. Interested Parties

* Haomai Wang (UnitedStack)

* Loic Dachary <loic@dachary.org>

* Name

h3. Current Status

We currently don't have any approach to create a WORM volume whatever librbd or rbd cli.

h3. Detailed Description

WORM (write once, read many) is a desired feature for users who want to store data such as 'log files', "config files",  and such like, where the data is not allowed to get modified. It is important for a distributed architecture to enjoy the mini version of shared filesystem.

WORM isn't the same as read-only(RO) volume, but the use cases RO volume fit into also can be applied to WORM. Folks can use WORM volume as shared-volume, read-only volume or others. WORM provide the ability to attach a single volume to multiple instances simultaneously and could be especially useful for things like Images and even D2D backups. 

Except the ability to create WORM volume, we should allow a normal volume to convert to WORM volume.

As ceph, we don't have many works todo. Just implements the feature in librbd and rbd.ko. 

h3. Work items

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h3. Build / release tasks

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h3. Documentation tasks

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h3. Deprecation tasks

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