Is it possible to know filesize in blocks and its distribution over DataNodes in Hadoop?
Currently I am using:
frolo#A11:~/hadoop> $HADOOP_HOME/bin/hadoop dfs -stat "%b %o %r %n" /user/frolo/input/rmat-*
318339 67108864 1 rmat-10.0
392835957 67108864 1 rmat-20.0
Which does not show actual number of blocks created after uploading file to HDFS. And I dont know any way how to find out its distribution.
Thanks,
Alex
The %r in your stat command shows the replication factor of the queried file. If this is 1, it means there will only be only a single replica across the cluster for blocks belonging to this file. The hadoop fs -ls output also shows this value for listed files as one of its numeric columns, as replication factor is a per file FS attribute.
If you are looking to find where the blocks reside instead, you are looking for hdfs fsck (or hadoop fsck if using a dated release) instead. The below, for example, will let you see the list of block IDs and their respective set of resident locations, for any file:
hdfs fsck /user/frolo/input/rmat-10.0 -files -blocks -locations
Related
In a cluster of hdfs, i receive multiple files on a daily basis which can be of 3 types :
1) product_info_timestamp
2) user_info_timestamp
3) user_activity_timestamp
The number of files received can be of any number but they will belong to one of these 3 categories only.
I want to merge all the files(after checking whether they are less than 100mb) belonging to one category into a single file.
for eg: 3 files named product_info_* should be merged into one file named product_info.
How do i achieve this?
You can use getmerge toachieve this, but the result will be stored in your local node (edge node), so you need to be sure you have enough space there.
hadoop fs -getmerge /hdfs_path/product_info_* /local_path/product_inf
You can move them back to hdfs with put
hadoop fs -put /local_path/product_inf /hdfs_path
You can use hadoop archive (.har file) or sequence file. It is very simple to use - just google "hadoop archive" or "sequence file".
Another set of commands along the similar lines as suggested by #SCouto
hdfs dfs -cat /hdfs_path/product_info_* > /local_path/product_info_combined.txt
hdfs dfs -put /local_path/product_info_combined.txt /hdfs_path/
I have a 1 GB file that I've put on HDFS. So, it would be broken into blocks and sent to different nodes in the cluster.
Is there any command to identify the exact size of the block of the file on a particular node?
Thanks.
You should use hdfs fsck command:
hdfs fsck /tmp/test.txt -files -blocks
This command will print information about all the blocks of which file consists:
/tmp/test.tar.gz 151937000 bytes, 2 block(s): OK
0. BP-739546456-192.168.20.1-1455713910789:blk_1073742021_1197 len=134217728 Live_repl=3
1. BP-739546456-192.168.20.1-1455713910789:blk_1073742022_1198 len=17719272 Live_repl=3
As you can see here is shown (len field in every row) actual used capacities of blocks.
Also there are many another useful features of hdfs fsck which you can see at the official Hadoop documentation page.
You can try:
hdfs getconf -confKey dfs.blocksize
I do not have reputation to comment.
Have a look at documentation page to set various properties, which covers
dfs.blocksize
Apart from configuration change, you can view actual size of file with
hadoop fs -ls fileNameWithPath
e.g.
hadoop fs -ls /user/edureka
output:
-rwxrwxrwx 1 edureka supergroup 391355 2014-09-30 12:29 /user/edureka/cust
I have multiple tables on my Hbase shell that I would like to copy onto my file system. Some tables exceed 100gb. However, I only have 55gb free space left in my local file system. Therefore, I would like to know the size of my hbase tables so that I could export only the small sized tables. Any suggestions are appreciated.
Thanks,
gautham
try
hdfs dfs -du -h /hbase/data/default/ (or /hbase/ depending on hbase version you use)
This will show how much space is used by files of your tables.
Hope that will help.
for 0.98+ try hadoop fs -du -s -h $hbase_root_dir/data/data/$schema_name/ (or /hbase/ for 0.94)
You can find hbase_root_dir from hbase-site.xml file of your cluster.
The above command will provide you summary of disk used by each table.
use du
Usage: hdfs dfs -du [-s] [-h] URI [URI …]
Displays sizes of files and directories contained in the given directory or the length of a file in case its just a file.
Options:
The -s option will result in an aggregate summary of file lengths being displayed, rather than the individual files.
The -h option will format file sizes in a "human-readable" fashion (e.g 64.0m instead of 67108864)
Example:
hdfs dfs -du -h /hbase/data/default
output for me:
1.2 M /hbase/data/default/kylin_metadata
14.0 K /hbase/data/default/kylin_metadata_acl
636 /hbase/data/default/kylin_metadata_user
5.6 K /hbase/data/default/test
Is there a way to find out where have the fragments of the file I have put in Hdfs gone? I mean the information as to where the file fragments stored in hdfs?
You can use the fsck command:
#> hadoop fsck /path/to/file -files -blocks -locations -racks
This lists for the file, the blocks and their associated metadata:
block name/ID
block length
block replication
locations (datanodeIp:port)
rack (prefix datanode ip's with the associated rack id)
For example:
/user/chris/file1.txt 123 bytes, 1 block(s): OK
0. blk_432678432632_3426532 len=123 repl=2 [/rack1/1.2.3.4:50010, /rack2/4.5.6.7:50010]
In Hadoop fs how to lookup the block size for a particular file?
I was primarily interested in a command line, something like:
hadoop fs ... hdfs://fs1.data/...
But it looks like that does not exist. Is there a Java solution?
The fsck commands in the other answers list the blocks and allow you to see the number of blocks. However, to see the actual block size in bytes with no extra cruft do:
hadoop fs -stat %o /filename
Default block size is:
hdfs getconf -confKey dfs.blocksize
Details about units
The units for the block size are not documented in the hadoop fs -stat command, however, looking at the source line and the docs for the method it calls we can see it uses bytes and cannot report block sizes over about 9 exabytes.
The units for the hdfs getconf command may not be bytes. It returns whatever string is being used for dfs.blocksize in the configuration file. (This is seen in the source for the final function and its indirect caller)
Seems hadoop fs doesn't have options to do this.
But hadoop fsck could.
You can try this
$HADOOP_HOME/bin/hadoop fsck /path/to/file -files -blocks
I think it should be doable with:
hadoop fsck /filename -blocks
but I get Connection refused
Try to code below
path=hdfs://a/b/c
size=`hdfs dfs -count ${path} | awk '{print $3}'`
echo $size
For displaying the actual block size of the existing file within HDFS I used:
[pety#master1 ~]$ hdfs dfs -stat %o /tmp/testfile_64
67108864