Database Reference
In-Depth Information
Table 11-2. dfsadmin commands
Command
Description
Shows help for a given command, or all commands if no command is specified.
-help
Shows filesystem statistics (similar to those shown in the web UI) and informa-
tion on connected datanodes.
-report
Dumps information to a file in Hadoop's log directory about blocks that are being
replicated or deleted, as well as a list of connected datanodes.
-metasave
-safemode
Saves the current in-memory filesystem image to a new
fsimage
file and resets the
edits
file. This operation may be performed only in safe mode.
-saveNamespace
Retrieves the latest
fsimage
from the namenode and saves it in a local file.
-fetchImage
Updates the set of datanodes that are permitted to connect to the namenode. See
-refreshNodes
-upgradeProgress
Gets information on the progress of an HDFS upgrade or forces an upgrade to
proceed. See
Upgrades
.
-finalizeUpgrade
Removes the previous version of the namenode and datanode storage directories.
Used after an upgrade has been applied and the cluster is running successfully on
the new version. See
Upgrades
.
Sets directory quotas. Directory quotas set a limit on the number of names (files
or directories) in the directory tree. Directory quotas are useful for preventing
users from creating large numbers of small files, a measure that helps preserve the
namenode's memory (recall that accounting information for every file, directory,
and block in the filesystem is stored in memory).
-setQuota
Clears specified directory quotas.
-clrQuota
Sets space quotas on directories. Space quotas set a limit on the size of files that
may be stored in a directory tree. They are useful for giving users a limited
amount of storage.
-setSpaceQuota
Clears specified space quotas.
-clrSpaceQuota
Refreshes the namenode's service-level authorization policy file.
-refreshSer-
viceAcl
Allows snapshot creation for the specified directory.
-allowSnapshot
-disallowSnapshot
Disallows snapshot creation for the specified directory.
