Andrew Wong created KUDU-2321:
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Summary: Allow Kudu to start up with missing data directories
Key: KUDU-2321
URL: https://issues.apache.org/jira/browse/KUDU-2321
Project: Kudu
Issue Type: Improvement
Components: fs, supportability
Reporter: Andrew Wong
Today, Kudu will refuse to start up when its FS layout isn't as expected.
Before 1.6.0, users could not add data directories; before 1.7.0, users could
not remove data directories; for both actions, users must use the `update_dirs`
tool.
Prior to this, the preferred way to start up a Kudu node with a different FS
layout was to rmrf the entirety of the node's FS layout and start a new
incarnation with a new UUID at the same location. While Kudu is designed to be
resilient to such removal of data (automatically replicating the removed
tablets to other nodes), this has lead to problems, as, e.g., wiping multiple
nodes without waiting ample time in between wipes could lead to data loss.
While the `update_dirs` tool removes the need for rmrf altogether, that may not
stop unknowing users from wiping their nodes clean. Now that we have a solution
to safe removal and addition of data directories with known constraints to its
usage, it's not unthinkable that we extend Kudu itself to start up with a
different FS layout subject to the same constraints.
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