Aasha Medhi created HDFS-14869:
----------------------------------

             Summary: Data loss in case of distcp using snapshot diff.
                 Key: HDFS-14869
                 URL: https://issues.apache.org/jira/browse/HDFS-14869
             Project: Hadoop HDFS
          Issue Type: Bug
          Components: distcp
            Reporter: Aasha Medhi


Steps to reproduce
 * Create a directory in hdfs to copy using distcp.
 * Include a staging folder in the directory.

{code:java}
[hdfs@ctr-e141-1563959304486-33995-01-000003 hadoop-mapreduce]$ hadoop fs -ls 
/tmp/tocopy
Found 4 items
-rw-r--r--   3 hdfs hdfs         16 2019-09-12 10:32 /tmp/tocopy/.b.txt
drwxr-xr-x   - hdfs hdfs          0 2019-09-23 09:18 /tmp/tocopy/.staging
-rw-r--r--   3 hdfs hdfs         12 2019-09-12 10:32 /tmp/tocopy/a.txt
-rw-r--r--   3 hdfs hdfs          4 2019-09-20 08:23 /tmp/tocopy/foo.txt{code}
 * The exclusion filter is set to exclude any staging directory

{code:java}
[hdfs@ctr-e141-1563959304486-33995-01-000003 hadoop-mapreduce]$ cat /tmp/filter
.*\.Trash.*
.*\.staging.*{code}
 * Do a copy using distcp snapshots, the staging directory is not replicated.

{code:java}
hadoop jar hadoop-distcp-3.3.0-SNAPSHOT.jar 
-Dmapreduce.job.user.classpath.first=true -filters /tmp/filter 
/tmp/tocopy/.snapshot/s1 /tmp/target

[hdfs@ctr-e141-1563959304486-33995-01-000003 root]$ hadoop fs -ls /tmp/target
Found 3 items
-rw-r--r--   3 hdfs hdfs         16 2019-09-24 06:56 /tmp/target/.b.txt
-rw-r--r--   3 hdfs hdfs         12 2019-09-24 06:56 /tmp/target/a.txt
-rw-r--r--   3 hdfs hdfs          4 2019-09-24 06:56 /tmp/target/foo.txt{code}
 * Rename the staging directory to final

{code:java}
[hdfs@ctr-e141-1563959304486-33995-01-000003 hadoop-mapreduce]$ hadoop fs -mv 
/tmp/tocopy/.staging /tmp/tocopy/final{code}
 * Do a copy using snapshot diff.

{code:java}
[hdfs@ctr-e141-1563959304486-33995-01-000003 hadoop-mapreduce]$ hdfs 
snapshotDiff /tmp/tocopy s1 s2[hdfs@ctr-e141-1563959304486-33995-01-000003 
hadoop-mapreduce]$ hdfs snapshotDiff /tmp/tocopy s1 s2Difference between 
snapshot s1 and snapshot s2 under directory /tmp/tocopy:M .R ./.staging -> 
./final

{code}
 * The diff report just has a rename record and the new final directory is 
never copied.

{code:java}
[hdfs@ctr-e141-1563959304486-33995-01-000003 hadoop-mapreduce]$ hadoop jar 
hadoop-distcp-3.3.0-SNAPSHOT.jar -Dmapreduce.job.user.classpath.first=true 
-filters /tmp/filter -diff s1 s2 -update /tmp/tocopy /tmp/target
19/09/24 07:05:32 INFO tools.DistCp: Input Options: 
DistCpOptions{atomicCommit=false, syncFolder=true, deleteMissing=false, 
ignoreFailures=false, overwrite=false, append=false, useDiff=true, 
useRdiff=false, fromSnapshot=s1, toSnapshot=s2, skipCRC=false, blocking=true, 
numListstatusThreads=0, maxMaps=20, mapBandwidth=0.0, 
copyStrategy='uniformsize', preserveStatus=[BLOCKSIZE], atomicWorkPath=null, 
logPath=null, sourceFileListing=null, sourcePaths=[/tmp/tocopy], 
targetPath=/tmp/target, filtersFile='/tmp/filter', blocksPerChunk=0, 
copyBufferSize=8192, verboseLog=false, directWrite=false}, 
sourcePaths=[/tmp/tocopy], targetPathExists=true, preserveRawXattrsfalse
19/09/24 07:05:32 INFO client.RMProxy: Connecting to ResourceManager at 
ctr-e141-1563959304486-33995-01-000003.hwx.site/172.27.68.128:8050
19/09/24 07:05:33 INFO client.AHSProxy: Connecting to Application History 
server at ctr-e141-1563959304486-33995-01-000003.hwx.site/172.27.68.128:10200
19/09/24 07:05:33 INFO tools.DistCp: Number of paths in the copy list: 0
19/09/24 07:05:33 INFO client.RMProxy: Connecting to ResourceManager at 
ctr-e141-1563959304486-33995-01-000003.hwx.site/172.27.68.128:8050
19/09/24 07:05:33 INFO client.AHSProxy: Connecting to Application History 
server at ctr-e141-1563959304486-33995-01-000003.hwx.site/172.27.68.128:10200
19/09/24 07:05:33 INFO mapreduce.JobResourceUploader: Disabling Erasure Coding 
for path: /user/hdfs/.staging/job_1568647978682_0010
19/09/24 07:05:34 INFO mapreduce.JobSubmitter: number of splits:0
19/09/24 07:05:34 INFO mapreduce.JobSubmitter: Submitting tokens for job: 
job_1568647978682_0010
19/09/24 07:05:34 INFO mapreduce.JobSubmitter: Executing with tokens: []
19/09/24 07:05:34 INFO conf.Configuration: found resource resource-types.xml at 
file:/etc/hadoop/3.1.4.0-272/0/resource-types.xml
19/09/24 07:05:34 INFO impl.YarnClientImpl: Submitted application 
application_1568647978682_0010
19/09/24 07:05:34 INFO mapreduce.Job: The url to track the job: 
http://ctr-e141-1563959304486-33995-01-000003.hwx.site:8088/proxy/application_1568647978682_0010/
19/09/24 07:05:34 INFO tools.DistCp: DistCp job-id: job_1568647978682_0010
19/09/24 07:05:34 INFO mapreduce.Job: Running job: job_1568647978682_0010
19/09/24 07:05:40 INFO mapreduce.Job: Job job_1568647978682_0010 running in 
uber mode : false
19/09/24 07:05:40 INFO mapreduce.Job:  map 0% reduce 0%
19/09/24 07:09:43 INFO mapreduce.Job: Job job_1568647978682_0010 completed 
successfully19/09/24 07:09:43 INFO mapreduce.Job: Job job_1568647978682_0010 
completed successfully19/09/24 07:09:43 INFO mapreduce.Job: Counters: 2 Job 
Counters Total time spent by all maps in occupied slots (ms)=0 Total time spent 
by all reduces in occupied slots (ms)=0 

[hdfs@ctr-e141-1563959304486-33995-01-000003 root]$ hadoop fs -ls /tmp/target
Found 3 items
-rw-r--r--   3 hdfs hdfs         16 2019-09-24 06:56 /tmp/target/.b.txt
-rw-r--r--   3 hdfs hdfs         12 2019-09-24 06:56 /tmp/target/a.txt
-rw-r--r--   3 hdfs hdfs          4 2019-09-24 06:56 /tmp/target/foo.txt

{code}
 



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