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Advanced O&M Command Reference
OceanStor 2800 V5 V500R007

This document is applicable to OceanStor 2800 V5. Based on the CLI, this document describes how to use various commands classified by functions and how to set the CLI and manage the storage system through these commands. The document that you browse online matches the latest C version of the product. Click Download to download documents of other C versions.

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show ddp compress_info

show ddp compress_info


The show ddp compress_info command is used to query compression information about a data block.


show ddp compress_info domain_id=? extent_id=? extent_offset=? storage_tier=? gang_flag=? controller=?





domain_id=? ID of the domain that you want to query.

To obtain the value, run the "show file_system general" or "show lun dedup_compress" command.

extent_id=? ID of the extent that you want to query.

The value ranges from 0 to 18,446,744,073,709,551,615.

extent_offset=? Offset of the extent that you want to query.

The value ranges from 0 to 4,294,967,295.

storage_tier=? Type of the storage media.

The value can be "SSD", "SAS", or "NearLine SAS", where:

  • "SSD": SSD.
  • "SAS ": SAS disk.
  • "NearLine SAS": NL-SAS disk.
gang_flag=? Gang chunk flag.

The value can be "true" or "false", where:

  • "true": gang chunk.
  • "false": non-gang chunk.
controller=? Controller ID.

The value is in the format of "XA" or "XB" or "XC" or "XD", where the "X" is an integer ranging from 0 to 3, for example: "0A", "1C".


Developer view

Usage Guidelines

Before running this command, specify a controller ID.


Query compression information about the data block with gang chunk flag "false" and storage media "SAS" on extent "72130162894987266" with offset "0" in domain "0".

developer:/>show ddp compress_info domain_id=0 extent_id=72130162894987266 extent_offset=0 storage_tier=SAS gang_flag=false controller=0A
  Is Compressed Data            : Yes       
  Tag                           : 3671775962 
  Original Data Checksum        : 3671775962 
  Compressed Data Checksum      : 651771316 
  Version                       : 16        
  Original Data Length          : 65536     
  Compressed Data Length        : 18908   
  Compress Algorithm            : 0         
  Compress Header Length        : 32        
  Block Number                  : 1         
  Private Length                : 4         
  Original Data Checksum Flag   : False     
  Compressed Data Checksum Flag : True      
  Block Length                  : 65536

System Response

The following table describes the parameter meanings.



Is Compressed Data

Whether data is compressed.


Compression flag.

Original Data Checksum

Check value of original data.

Compressed Data Checksum

Check value of compressed data.


Version of the compression algorithm library.

Original Data Length

Length of original data.

Compressed Data Length

Length of compressed data.

Compress Algorithm

Compression algorithm.

Compress Header Length

Length of the compression header.

Block Number

Number of blocks that are compressed together.

Private Length

Length of compressed private information.

Original Data Checksum Flag

Check flag of original data.

Compressed Data Checksum Flag

Check flag of compressed data.

Block Length

Length of the combined block.

Updated: 2020-03-19

Document ID: EDOC1000181575

Views: 784486

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