question How to speed up "hdfs dfs -mv" for more than 30 000 files ? in Archives of Support Questions (Read Only)

How to speed up "hdfs dfs -mv" for more than 30 000 files ?

thierry_vernhet — Wed, 25 Oct 2017 19:07:57 GMT

Hello,

I've got 30 thousand of files to move to another hdfs directory.

Do you know a better way than "hdfs dfs -mv /mydirectory/* /targetdirectory" to go faster ?

Average size of a file : 10 Kb.

And I can't merge the files in a bigger one before.

Thanks for your feedback

Re: How to speed up "hdfs dfs -mv" for more than 30 000 files ?

kgautam — Wed, 25 Oct 2017 19:12:59 GMT

1. dfs -mv is the fastest as compare to -cp or distcp .
If possible move mydirectory instead of mydirectory/* into /targetdirectory

Re: How to speed up "hdfs dfs -mv" for more than 30 000 files ?

thierry_vernhet — Wed, 25 Oct 2017 19:22:24 GMT

Thanks

Not possible because the result is /targetdirectory/mydirectory and I expect all the files moved in path /targetdirectory/*

Re: How to speed up "hdfs dfs -mv" for more than 30 000 files ?

asirna — Wed, 25 Oct 2017 19:29:09 GMT

@Thierry Vernhet,

If there are less files in /targetdirectory than the /mydirectory , you can do the below

hdfs dfs -mv /targetdirectory /x
hdfs dfs -mv /mydirectory /targetdirectory
hdfs dfs -mv /x/* /targetdirectory

Thanks,

Aditya

Re: How to speed up "hdfs dfs -mv" for more than 30 000 files ?

thierry_vernhet — Wed, 25 Oct 2017 20:04:34 GMT

Thanks but it doesn't work for the same reason.

When you "mv /mydirectory /targetdirectory" the result is always /targetdirectory/mydirectory.

Re: How to speed up "hdfs dfs -mv" for more than 30 000 files ?

asirna — Wed, 25 Oct 2017 20:17:56 GMT

@Thierry Vernhet,

After running the first command targetdirectory will be renamed to x.

So mv /mydirectory /targetdirectory is not /targetdirectory/mydirectory , instead it will just rename mydirectory to targetdirectory since the destination directory doesn't exist.

So, if targetdirectory has less files this is an option.Instead of moving 30k files, you can move less files

Thanks,

Aditya

Re: How to speed up "hdfs dfs -mv" for more than 30 000 files ?

thierry_vernhet — Wed, 25 Oct 2017 20:36:55 GMT

@Aditya Sirna,

Of course... I'm going to try this.

Thanks

Re: How to speed up "hdfs dfs -mv" for more than 30 000 files ?

divakarreddy_a — Wed, 25 Oct 2017 20:54:30 GMT

@Thierry Vernhet

If you have more than 10 GB, I'd recommend use distcp instead of using Copy OR Move.