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Thu, 09 Aug 2007

Initial mirroring implementation entered testing stage.

So far it does not support sync on recover, it only puts dirty bits for missed chunks in the per-node bitmap and continues to work with other nodes in the mirror.
Code supports any number of devices in the mirror.
Fancy reconnection logic allows to turn off any mirror nodes, and later system will reconnect to them and start writing data to. Sync will be done at reconnection time.
As a bonus, one can remove mirror from the storage (physically disconnect a wire for example) and mount it locally. This works in the simplest case without linear mapping on top/under the given node of course (since otherwise system state is distributed between given node and some others), such functionality can be used as live backup - just mount it when node is offline, and all your data is there.

Resync code will select first node, which has given chunk uptodate, and fetch data from it.
Stay tuned.

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