[HBASE-8352] Rename '.snapshot' directory

• Type: Bug
• Status: Closed
• Priority: Blocker
• Resolution: Fixed
• Fix Version/s: 0.98.0, 0.94.7, 0.95.1
• Hadoop Flags: Incompatible change, Reviewed

Release Note

In order to avoid name collision with hdfs snapshot, ".snapshot" under HBase root directory must be renamed as ".hbase-snapshot" before deployment of 0.94.7 or later release is started.

Don't do rolling upgrade between 0.94.6.1 and 0.94.7 if there're on-going snapshots activities.
Sequence of actions should be:

1. make sure all on-going snapshots activities have completed
2. shutdown all the masters
3. rename ".snapshot" under HBase root directory as ".hbase-snapshot"
4. upgrade the masters to 0.94.7+ release (You now can perform clone or restore, but not taking snapshots)
5. upgrade the region servers
(You should not take snapshots until all the regions server are aligned to 0.94.7+ release)

If you take a snapshot during the RS upgrades nothing critical happens. The ".snapshot" folder would appear again and the snapshot will fail since half of the data will be in ".hbase-snapshot" and the other half in ".snapshot"

• Assignee: Ted Yu
• Reporter: Ted Yu
• Created: 16/Apr/13 06:10
• Updated: 27/Apr/13 15:55
• Resolved: 17/Apr/13 00:14

Description

Testing HBase Snapshot on top of Hadoop's Snapshot branch (http://svn.apache.org/viewvc/hadoop/common/branches/HDFS-2802/), we found that both features used '.snapshot' directory to store metadata.

HDFS (built from HDFS-2802 branch) doesn't allow paths with .snapshot as a component

From discussion on [e-mail], (see http://search-hadoop.com/m/kY6C3cXMs51), consensus was to rename '.snapshot' directory in HBase so that both features can co-exist smoothly.

Issue Links

• relates to: HDFS-4666 Disallow users to create file/dir named ".snapshot"