Hi My problem is not that my data is under replicated. I have 3 data nodes. In my hadoop-site.xml I also set the configuration as:
<property> <name>dfs.replication</name> <value>2</value> </property> But after this also data is replicated on 3 nodes instead of two nodes. Now, please tell what can be the problem? Thanks & Regards Aseem Puri -----Original Message----- From: Raghu Angadi [mailto:rang...@yahoo-inc.com] Sent: Wednesday, April 15, 2009 2:58 AM To: core-user@hadoop.apache.org Subject: Re: More Replication on dfs Aseem, Regd over-replication, it is mostly app related issue as Alex mentioned. But if you are concerned about under-replicated blocks in fsck output : These blocks should not stay under-replicated if you have enough nodes and enough space on them (check NameNode webui). Try grep-ing for one of the blocks in NameNode log (and datnode logs as well, since you have just 3 nodes). Raghu. Puri, Aseem wrote: > Alex, > > Ouput of $ bin/hadoop fsck / command after running HBase data insert > command in a table is: > > ..... > ..... > ..... > ..... > ..... > /hbase/test/903188508/tags/info/4897652949308499876: Under replicated > blk_-5193 > 695109439554521_3133. Target Replicas is 3 but found 1 replica(s). > . > /hbase/test/903188508/tags/mapfiles/4897652949308499876/data: Under > replicated > blk_-1213602857020415242_3132. Target Replicas is 3 but found 1 > replica(s). > . > /hbase/test/903188508/tags/mapfiles/4897652949308499876/index: Under > replicated > blk_3934493034551838567_3132. Target Replicas is 3 but found 1 > replica(s). > . > /user/HadoopAdmin/hbase table.doc: Under replicated > blk_4339521803948458144_103 > 1. Target Replicas is 3 but found 2 replica(s). > . > /user/HadoopAdmin/input/bin.doc: Under replicated > blk_-3661765932004150973_1030 > . Target Replicas is 3 but found 2 replica(s). > . > /user/HadoopAdmin/input/file01.txt: Under replicated > blk_2744169131466786624_10 > 01. Target Replicas is 3 but found 2 replica(s). > . > /user/HadoopAdmin/input/file02.txt: Under replicated > blk_2021956984317789924_10 > 02. Target Replicas is 3 but found 2 replica(s). > . > /user/HadoopAdmin/input/test.txt: Under replicated > blk_-3062256167060082648_100 > 4. Target Replicas is 3 but found 2 replica(s). > ... > /user/HadoopAdmin/output/part-00000: Under replicated > blk_8908973033976428484_1 > 010. Target Replicas is 3 but found 2 replica(s). > Status: HEALTHY > Total size: 48510226 B > Total dirs: 492 > Total files: 439 (Files currently being written: 2) > Total blocks (validated): 401 (avg. block size 120973 B) (Total > open file > blocks (not validated): 2) > Minimally replicated blocks: 401 (100.0 %) > Over-replicated blocks: 0 (0.0 %) > Under-replicated blocks: 399 (99.50124 %) > Mis-replicated blocks: 0 (0.0 %) > Default replication factor: 2 > Average block replication: 1.3117207 > Corrupt blocks: 0 > Missing replicas: 675 (128.327 %) > Number of data-nodes: 2 > Number of racks: 1 > > > The filesystem under path '/' is HEALTHY > Please tell what is wrong. > > Aseem > > -----Original Message----- > From: Alex Loddengaard [mailto:a...@cloudera.com] > Sent: Friday, April 10, 2009 11:04 PM > To: core-user@hadoop.apache.org > Subject: Re: More Replication on dfs > > Aseem, > > How are you verifying that blocks are not being replicated? Have you > ran > fsck? *bin/hadoop fsck /* > > I'd be surprised if replication really wasn't happening. Can you run > fsck > and pay attention to "Under-replicated blocks" and "Mis-replicated > blocks?" > In fact, can you just copy-paste the output of fsck? > > Alex > > On Thu, Apr 9, 2009 at 11:23 PM, Puri, Aseem > <aseem.p...@honeywell.com>wrote: > >> Hi >> I also tried the command $ bin/hadoop balancer. But still the >> same problem. >> >> Aseem >> >> -----Original Message----- >> From: Puri, Aseem [mailto:aseem.p...@honeywell.com] >> Sent: Friday, April 10, 2009 11:18 AM >> To: core-user@hadoop.apache.org >> Subject: RE: More Replication on dfs >> >> Hi Alex, >> >> Thanks for sharing your knowledge. Till now I have three >> machines and I have to check the behavior of Hadoop so I want >> replication factor should be 2. I started my Hadoop server with >> replication factor 3. After that I upload 3 files to implement word >> count program. But as my all files are stored on one machine and >> replicated to other datanodes also, so my map reduce program takes > input >> from one Datanode only. I want my files to be on different data node > so >> to check functionality of map reduce properly. >> >> Also before starting my Hadoop server again with replication >> factor 2 I formatted all Datanodes and deleted all old data manually. >> >> Please suggest what I should do now. >> >> Regards, >> Aseem Puri >> >> >> -----Original Message----- >> From: Mithila Nagendra [mailto:mnage...@asu.edu] >> Sent: Friday, April 10, 2009 10:56 AM >> To: core-user@hadoop.apache.org >> Subject: Re: More Replication on dfs >> >> To add to the question, how does one decide what is the optimal >> replication >> factor for a cluster. For instance what would be the appropriate >> replication >> factor for a cluster consisting of 5 nodes. >> Mithila >> >> On Fri, Apr 10, 2009 at 8:20 AM, Alex Loddengaard <a...@cloudera.com> >> wrote: >> >>> Did you load any files when replication was set to 3? If so, you'll >> have >>> to >>> rebalance: >>> >>> > <http://hadoop.apache.org/core/docs/r0.19.1/commands_manual.html#balance >> r> >>> < >>> > http://hadoop.apache.org/core/docs/r0.19.1/hdfs_user_guide.html#Rebalanc >> er >>> Note that most people run HDFS with a replication factor of 3. > There >> have >>> been cases when clusters running with a replication of 2 discovered >> new >>> bugs, because replication is so often set to 3. That said, if you > can >> do >>> it, it's probably advisable to run with a replication factor of 3 >> instead >>> of >>> 2. >>> >>> Alex >>> >>> On Thu, Apr 9, 2009 at 9:56 PM, Puri, Aseem > <aseem.p...@honeywell.com >>>> wrote: >>>> Hi >>>> >>>> I am a new Hadoop user. I have a small cluster with 3 >>>> Datanodes. In hadoop-site.xml values of dfs.replication property > is >> 2 >>>> but then also it is replicating data on 3 machines. >>>> >>>> >>>> >>>> Please tell why is it happening? >>>> >>>> >>>> >>>> Regards, >>>> >>>> Aseem Puri >>>> >>>> >>>> >>>> >>>> >>>>