Simplify generation stamp upgrade by making is a local upgrade on datandodes. Deleted distributed upgrade.
- The generation stamp upgrade renames blocks' meta-files so that the name contains the block generation stamp as stated in
If a data-node has blocks that do not belong to any files and the name-node asks the data-node to remove those blocks
during or before the upgrade started the data-node will remove the blocks but not the meta-files because their names
are still in the old format which is not recognized by the new code. So we can end up with a number of garbage files which
will be hard to recognize that they are unused and the system will never remove them automatically.
I think this should be handled by the upgrade code in the end, but may be it will be right to fix
HADOOP-3002for the 0.18 release,
which will avoid scheduling block removal when the name-node is in safe-mode.
- I was not able to get the upgrade -force option to work. This option lets the name-node proceed with a distributed upgrade even if
the data-nodes are not able to complete their local upgrades. Did we test this feature at all for the generation stamp upgrade?