Hadoop Hbase Upgrade

Hadoop HDFS and HBase upgrade notes

Because the hadoop1.0.2,hbase used previously was hbase-0.92.1 but an accident resulted in metadata loss, and the class that fixes the metadata itself has bugs
So there are only two paths in sight:
1, modify HBase source code recompile hbase fix bugs
2, upgrade to the next version, and this version has been fixed this bug from release node to see 0.92.2 and later versions have fixed the bug
So decided to upgrade to the latest stable version of hbase-0.94.3 and this version of the hbase and hadoop-1.0.4 compatibility is the best, so the Hadoop joint upgrade to hadoop-1.0.4

1. Hadoop Upgrade steps:
(1) Stop all Mr Tasks on the cluster, including HBase (if HBase is in use, stop first, then zookeeper)
(2) Stop DFS (1, 22 steps can also be closed after hbase and zookeeper are closed using stop-all.sh script)
(3) Delete temporary data, that is, the file in the file directory of the Hadoop.tmp.dir value set in Core-site.xml
(4) Backing up HDFs meta data

(5) will download the good hadoop-1.0.4.tar.gz to install the directory, I here is/home/hbase, and renamed to Hadoop, and configure hadoop/conf under the corresponding file
(6) Configure environment variables such as hadoop_home, hadoop_home_conf, etc. (if you upgrade the HADOOP installation directory with the original inconsistency)
(7) Upgrade using the Start-dfs.sh-upgrade command under Hadoop_home/bin
(8) After waiting for upgrade, use the Hadoop fsck-blocks under Hadoop_home/bin to see if HDFs is complete and healthy
(9) When the cluster is normal and running for a period of time (if you are sure that there is no data loss, you can immediately final), the use of Hadoop Dfsadmin-finalizeupgrade version of serialization (before this if you did not delete the original version of Hadoop, You can use Start-dfs.sh-rollback to return to the original version of Hadoop.
After Finalizeupgrade, you need to restart the cluster, the space will be released, or Hadoop namenode-finalize

2. HBase Upgrade steps:
(1) When the Hadoop upgrade succeeded, the hbase-0.94.3.tar.gz will be extracted to the directory to be installed, I am here/home/hbase, and renamed to HBase
(2) Configure the files in the new hbase under Conf (as you first install hbase)
(3) If necessary, also modify environment variables, such as hbase_home, etc.
(4) Start zookeeper
(5) Start the new HBase
(6) Use web monitoring or hbase shell to check whether the data in HBase is intact

3.hadoop Upgrade Monitoring

Bin/hadoop dfsadmin-upgradeprogress
command to view the version upgrade.
Bin/hadoop dfsadmin-upgradeprogress Details
To see more details.
When the upgrade process is blocked, you can use the
Bin/hadoop dfsadmin-upgradeprogress Force
To force the upgrade to continue (This command is more dangerous and prudent to use).

When the HDFs is upgraded, Hadoop retains information about the old version.
So that you can easily demote the HDFs operation.
You can use Bin/start-dfs.sh-rollback to perform a demotion operation.