What does hdfs cacheadmin command do ? and what is cache pools?

[DataFlair Team]

What does hdfs cacheadmin command do ? and what is cache pools?

[DataFlair Team]

cacheadmin commands and cache pools

By using hdfs cacheadmin subcommand, administrators and users can interact with cache pools and directives, On the command-line.

Though, by a unique, non-repeating 64-bit integer ID, Cache directives are identified. Although, even if a cache directive is later removed, IDs will not be reused.

And, by a unique string name, Cache pools are identified.

– Cache directive commands

i. addDirective Command
Usage: hdfs cacheadmin -addDirective -path <path> -pool <pool-name> [-force] [-replication <replication>] [-ttl <time-to-live>]

It helps to add a new cache directive.

ii. removeDirective
Usage: hdfs cacheadmin -removeDirective <id>

It helps to remove a cache directive.

iii. removeDirectives
Usage: hdfs cacheadmin -removeDirectives <path>

It helps to remove every cache directive with the specified path.

iv. listDirectives
Usage: hdfs cacheadmin -listDirectives [-stats] [-path <path>] [-pool <pool>]

It helps to list cache directives.

– Cache pool commands

i.addPool
Usage: hdfs cacheadmin -addPool <name> [-owner <owner>] [-group <group>] [-mode <mode>] [-limit <limit>] [-maxTtl <maxTtl>

It helps to add a new cache pool.

ii. modifyPool
Usage: hdfs cacheadmin -modifyPool <name> [-owner <owner>] [-group <group>] [-mode <mode>] [-limit <limit>] [-maxTtl <maxTtl>]

iii. removePool
Usage: hdfs cacheadmin -removePool <name>

It helps to remove a cache pool. Also, it uncaches paths which are associated with the pool.

iv. listPools
Usage: hdfs cacheadmin -listPools [-stats] [<name>]

This command helps to display information about one or more cache pools, for example, name, owner, group, permissions, etc.

v. help
Usage: hdfs cacheadmin -help <command-name>

It helps to get detailed help about a command.

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