[HADOOP-3677] Problems with generation stamp upgrade

• Type: Bug
• Status: Closed
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 0.18.0
• Fix Version/s: 0.18.0
• Release Note: Simplify generation stamp upgrade by making is a local upgrade on datandodes. Deleted distributed upgrade.
• Assignee: Raghu Angadi
• Reporter: Konstantin Shvachko
• Created: 01/Jul/08 19:27
• Updated: 08/Jul/09 16:43
• Resolved: 17/Jul/08 18:25

Description

1. The generation stamp upgrade renames blocks' meta-files so that the name contains the block generation stamp as stated in HADOOP-2656.
   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-3002 for the 0.18 release,
   which will avoid scheduling block removal when the name-node is in safe-mode.
2. 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?

Issue Links

• relates to: HADOOP-3002 HDFS should not remove blocks while in safemode.