A comparison between BookKeeper and GlusterFS.

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AFR replicates by write all changes to all child translators, much like RAID1. If a child is down, write will go to the other children. If all children go offline, the volume itself goes offline.

Consistency issues.

Imagine a system with a AFR translator replicating to two Posix translators (A & B). If one replica(A) goes offline, a client will continue to write to the other (B). Now, B goes offline. The client will stop writing to any replica. A is restarted so the client can continue writing. The client writes updates to A. Now A and B are inconsistent.

Differences to BookKeeper

1 http://www.gluster.com/community/documentation/index.php/GlusterFS_Concepts^{Image Removed}
2 http://www.gluster.com/community/documentation/index.php/Understanding_AFR_Translator^{Image Removed}