[HDFS-13764] [DOC] update flag is not necessary to avoid verifying checksums

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Won't Fix
• Affects Version/s: 2.7.0, 2.7.3
• Component/s: documentation
• Assignee: Unassigned
• Reporter: Yuexin Zhang
• Created: 25/Jul/18 06:09
• Updated: 26/Jul/18 06:50
• Resolved: 26/Jul/18 06:50

Description

We mentioned to use "-update" option to avoid checksum in the following doc:

https://hadoop.apache.org/docs/r2.7.3/hadoop-project-dist/hadoop-hdfs/TransparentEncryption.html#Copying_between_encrypted_and_unencrypted_locations

Copying between encrypted and unencrypted locations
By default, distcp compares checksums provided by the filesystem to verify that the data was successfully copied to the destination. When copying between an unencrypted and encrypted location, the filesystem checksums will not match since the underlying block data is different. In this case, specify the -skipcrccheck and -update distcp flags to avoid verifying checksums.

 

But actually, "-update" option is not necessary, only "-skipcrccheck" is needed. Can we change it to:

 

Copying between encrypted and unencrypted locations
By default, distcp compares checksums provided by the filesystem to verify that the data was successfully copied to the destination. When copying between an unencrypted and encrypted location, the filesystem checksums will not match since the underlying block data is different. In this case, specify the -skipcrccheck flags to avoid verifying checksums.