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https://issues.apache.org/jira/browse/HDFS-2231?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13080279#comment-13080279
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Suresh Srinivas commented on HDFS-2231:
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h2. Current namenode and related configuration:
h3. Configuration that does not change for HA
*BackupNode related:*
DFS_NAMENODE_BACKUP_ADDRESS_KEY, DFS_NAMENODE_BACKUP_HTTP_ADDRESS_KEY,
DFS_NAMENODE_BACKUP_SERVICE_RPC_ADDRESS_KEY
*Secondary namenode related*
DFS_NAMENODE_SECONDARY_HTTP_ADDRESS_KEY,
DFS_SECONDARY_NAMENODE_KEYTAB_FILE_KEY, DFS_SECONDARY_NAMENODE_USER_NAME_KEY,
DFS_SECONDARY_NAMENODE_KRB_HTTPS_USER_NAME_KEY
*Checkpointer related*
DFS_NAMENODE_CHECKPOINT_PERIOD_KEY, DFS_NAMENODE_CHECKPOINT_SIZE_KEY,
DFS_NAMENODE_CHECKPOINT_DIR_KEY, DFS_NAMENODE_CHECKPOINT_EDITS_DIR_KEY
h3. Common configuration for active and standby (Set 1)
DFS_NAMENODE_SAFEMODE_EXTENSION_KEY, DFS_NAMENODE_SAFEMODE_THRESHOLD_PCT_KEY,
DFS_NAMENODE_HOSTS_KEY, DFS_NAMENODE_HOSTS_EXCLUDE_KEY,
DFS_NAMENODE_DECOMMISSION_INTERVAL_KEY,
DFS_NAMENODE_DECOMMISSION_NODES_PER_INTERVAL_KEY,
DFS_NAMENODE_HANDLER_COUNT_KEY, DFS_NAMENODE_SERVICE_HANDLER_COUNT_KEY,
DFS_NAMENODE_PLUGINS_KEY, DFS_NAMENODE_STARTUP_KEY,
DFS_NAMENODE_NAME_CACHE_THRESHOLD_KEY, DFS_NAMENODE_MAX_OBJECTS_KEY,
DFS_NAMENODE_UPGRADE_PERMISSION_KEY,
DFS_NAMENODE_HEARTBEAT_RECHECK_INTERVAL_KEY,
DFS_NAMENODE_ACCESSTIME_PRECISION_KEY,
DFS_NAMENODE_REPLICATION_CONSIDERLOAD_KEY,
DFS_NAMENODE_REPLICATION_INTERVAL_KEY, DFS_NAMENODE_REPLICATION_MIN_KEY,
DFS_NAMENODE_REPLICATION_PENDING_TIMEOUT_SEC_KEY,
DFS_NAMENODE_REPLICATION_MAX_STREAMS_KEY,
DFS_NAMENODE_DELEGATION_KEY_UPDATE_INTERVAL_KEY,
DFS_NAMENODE_DELEGATION_TOKEN_RENEW_INTERVAL_KEY,
DFS_NAMENODE_DELEGATION_TOKEN_MAX_LIFETIME_KEY,
DFS_NAMENODE_MAX_COMPONENT_LENGTH_KEY, DFS_NAMENODE_MAX_DIRECTORY_ITEMS_KEY,
DFS_NAMENODE_KEYTAB_FILE_KEY, DFS_NAMENODE_USER_NAME_KEY,
DFS_NAMENODE_KRB_HTTPS_USER_NAME_KEY
h3. Configurtion that is different for active and standby (Set 2)
*Address configuration:*
FS_DEFAULT_NAME_KEY, DFS_NAMENODE_RPC_ADDRESS_KEY,
DFS_NAMENODE_SERVICE_RPC_ADDRESS_KEY, DFS_NAMENODE_HTTP_ADDRESS_KEY,
DFS_NAMENODE_HTTPS_ADDRESS_KEY
*Storage directories* (external nfs storage dir could be different for
active/standby)
DFS_NAMENODE_NAME_DIR_KEY, DFS_NAMENODE_EDITS_DIR_KEY
h3. Unused
DFS_NAMENODE_NAME_DIR_RESTORE_KEY // Will remove this in a separate patch
h2. Configuration requirements for HA
*Terminology:*
# NNAddress1, NNAddress2 - address of individual NNs
# NNActiveAddress - Where the active provides namenode service.
# NNStandbyAddress - Where the standby namenode service such as read-only
operations.
# NNVIPAddress/FailoverAddress - this is the VIP address used by HA setup. This
address is owned by the active namenode and NNActiveAddress is same as
NNVIPAddress.
*Requirements:*
# Existing deployments must be able to use the configuration without any change.
# Datanodes and client need to know either through configuration or mechanism
such as ZooKeeper, both the namenodes, that is, active and standby.
# As much as possible the configuration for all the nodes must be the same. The
special configuration required for different node types should be minimmal.
h3. HA solution uses VIP address
# System needs to be configured with three sets of addresses, NNVIPAddress,
NNAddress1 and NNAddress2.
# Clients and datanodes use NNVIPAddress as NNActiveAddress.
# To discover NNStandbyAddress clients and datanode may try NNAddress1 and
NNAddress2 or use mechanism such as Zookeeper.
h3. Active and Standby namenode addresses without VIP address
# This setup does not require NNVIPAddress.
# To discover NNActiveAddress and NNStandbyAddress clients and datanodes may
try NNAddress1 and NNAddress2 or use mechanism such as Zookeeper.
h2. Proposal
h3. For VIP based solutions
# NNVIPAddress related configuration goes into configuration (Set 1 above). I
propose using the existing keys: DFS_NAMENODE_RPC_ADDRESS_KEY,
DFS_NAMENODE__SERVICE_RPC_ADDRESS_KEY, DFS_NAMENODE_HTTP_ADDRESS_KEY,
DFS_NAMENODE_HTTPS_ADDRESS_KEY - Try using existing params and add new params
for nn1 and nn2
# The active namenode uses this information to start services at appropriate
addresses.
h3. Generic part common to both VIP and non VIP based solution:*
*How do we add both namenodes into a common configuration?*
Datanodes need to know both the namenode addresses. Doing it in a single config
file enables this.
To do this, I propse adding:
DFS_NAMENODE_IDS (dfs.namenode.ids) and comma separated list of ids (any
appropriate string). Add (Set 2) suffixed with "." + <NamenodeID>.
The client and datanodes can read DFS_NAMENODES and use the suffix to get
corresponding parameters to load.
*How does namenode know its NamenodeID and what configuration parameters to
load?*
Namenode discovers its own configuration from parameter DFS_NAMENODE_ID
(dfs.namenode.id). On namenodes an xml include points to a file with a
parameter DFS_NAMENODE_ID with corresponding NamenodeID. On other nodes such as
datanodes and client gateway machines the xml include points an empty file.
Example:
{noformat}
<property>
<name>dfs.namenode.ids</name>
<value>nn1, nn2</value>
</property>
<property>
<name>dfs.namenode.rpc-address</name>
<value>host1:port</value>
</property>
<property>
<name>dfs.namenode.rpc-address.nn1</name>
<value>host1:port</value>
</property>
<property>
<name>dfs.namenode.rpc-address.nn2</name>
<value>host2:port</value>
</property>
{noformat}
> Configuration changes for HA namenode
> -------------------------------------
>
> Key: HDFS-2231
> URL: https://issues.apache.org/jira/browse/HDFS-2231
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Suresh Srinivas
> Assignee: Suresh Srinivas
> Fix For: HA branch (HDFS-1623)
>
>
> This jira tracks the changes required for configuring HA setup for namenodes.
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