I wasnt aware of data node level balancer procedure , I was thinking about the hdfs balancer . http://wiki.apache.org/hadoop/FAQ#On_an_individual_data_node.2C_how_do_you_balance_the_blocks_on_the_disk.3F
Thanks, Rahul On Fri, Jun 14, 2013 at 5:50 PM, Rahul Bhattacharjee < [email protected]> wrote: > Thanks Sandeep, > > I was thinking that the overall hdfs cluster might get unbalanced over the > time and balancer might be useful in that case. > I was more interested to know why only one disk out of configured 4 disks > of the DN is getting all the writes.As per whatever I have read , writes > should be in round robin fashion , which should ideally lead to all the > configured disks in the DN to be similarly loaded. > > Not sure how the balancer is fixing this issue. > > Rgds, > Rahul > > > > On Fri, Jun 14, 2013 at 4:45 PM, Sandeep L <[email protected]>wrote: > >> Rahul, >> >> In general this issue happens some times in Hadoop. There is no exact >> reason for this. >> To mitigate this you need to run balancer in regular intervals. >> >> Thanks, >> Sandeep. >> >> ------------------------------ >> Date: Fri, 14 Jun 2013 16:39:02 +0530 >> Subject: Re: Application errors with one disk on datanode getting filled >> up to 100% >> From: [email protected] >> To: [email protected] >> >> >> No, as of this moment we've no ideas about the reasons for that behavior. >> >> >> On Fri, Jun 14, 2013 at 4:04 PM, Rahul Bhattacharjee < >> [email protected]> wrote: >> >> Thanks Mayank, Any clue on why was only one disk was getting all writes. >> >> Rahul >> >> >> On Thu, Jun 13, 2013 at 11:47 AM, Mayank <[email protected]> wrote: >> >> So we did a manual rebalance (followed instructions at: >> http://wiki.apache.org/hadoop/FAQ#On_an_individual_data_node.2C_how_do_you_balance_the_blocks_on_the_disk.3F) >> and also reserved 30 GB of space for non dfs usage via >> dfs.datanode.du.reserved and restarted our apps. >> >> Things have been going fine till now. >> >> Keeping fingers crossed :) >> >> >> On Wed, Jun 12, 2013 at 12:58 PM, Rahul Bhattacharjee < >> [email protected]> wrote: >> >> I have a few points to make , these may not be very helpful for the said >> problem. >> >> +All data nodes are bad exception is kind of not pointing to the problem >> related to disk space full. >> +hadoop.tmp.dir acts as base location of other hadoop related properties >> , not sure if any particular directory is created specifically. >> +Only one disk getting filled looks strange.The other disk are part while >> formatting the NN. >> >> Would be interesting to know the reason for this. >> Please keep posted. >> >> Thanks, >> Rahul >> >> >> On Mon, Jun 10, 2013 at 3:39 PM, Nitin Pawar <[email protected]>wrote: >> >> From the snapshot, you got around 3TB for writing data. >> >> Can you check individual datanode's storage health. >> As you said you got 80 servers writing parallely to hdfs, I am not sure >> can that be an issue. >> As suggested in past threads, you can do a rebalance of the blocks but >> that will take some time to finish and will not solve your issue right >> away. >> >> You can wait for others to reply. I am sure there will be far better >> solutions from experts for this. >> >> >> On Mon, Jun 10, 2013 at 3:18 PM, Mayank <[email protected]> wrote: >> >> No it's not a map-reduce job. We've a java app running on around 80 >> machines which writes to hdfs. The error that I'd mentioned is being thrown >> by the application and yes we've replication factor set to 3 and following >> is status of hdfs: >> >> Configured Capacity : 16.15 TB DFS Used : 11.84 TB Non DFS Used : 872.66 >> GB DFS Remaining : 3.46 TB DFS Used% : 73.3 % DFS Remaining% : 21.42 % Live >> Nodes<http://hmaster.production.indix.tv:50070/dfsnodelist.jsp?whatNodes=LIVE> >> :10 Dead >> Nodes<http://hmaster.production.indix.tv:50070/dfsnodelist.jsp?whatNodes=DEAD> >> : 0 Decommissioning >> Nodes<http://hmaster.production.indix.tv:50070/dfsnodelist.jsp?whatNodes=DECOMMISSIONING> >> : 0 Number of Under-Replicated Blocks : 0 >> >> >> On Mon, Jun 10, 2013 at 3:11 PM, Nitin Pawar <[email protected]>wrote: >> >> when you say application errors out .. does that mean your mapreduce job >> is erroring? In that case apart from hdfs space you will need to look at >> mapred tmp directory space as well. >> >> you got 400GB * 4 * 10 = 16TB of disk and lets assume that you have a >> replication factor of 3 so at max you will have datasize of 5TB with you. >> I am also assuming you are not scheduling your program to run on entire >> 5TB with just 10 nodes. >> >> i suspect your clusters mapred tmp space is getting filled in while the >> job is running. >> >> >> >> >> >> On Mon, Jun 10, 2013 at 3:06 PM, Mayank <[email protected]> wrote: >> >> We are running a hadoop cluster with 10 datanodes and a namenode. Each >> datanode is setup with 4 disks (/data1, /data2, /data3, /data4), which each >> disk having a capacity 414GB. >> >> >> hdfs-site.xml has following property set: >> >> <property> >> <name>dfs.data.dir</name> >> >> <value>/data1/hadoopfs,/data2/hadoopfs,/data3/hadoopfs,/data4/hadoopfs</value> >> <description>Data dirs for DFS.</description> >> </property> >> >> Now we are facing a issue where in we find /data1 getting filled up >> quickly and many a times we see it's usage running at 100% with just few >> megabytes of free space. This issue is visible on 7 out of 10 datanodes at >> present. >> >> We've some java applications which are writing to hdfs and many a times >> we are seeing foloowing errors in our application logs: >> >> >> >> java.io.IOException: All datanodes xxx.xxx.xxx.xxx:50010 are bad. Aborting... >> at >> org.apache.hadoop.hdfs.DFSClient$DFSOutputStream.processDatanodeError(DFSClient.java:3093) >> at >> org.apache.hadoop.hdfs.DFSClient$DFSOutputStream.access$2200(DFSClient.java:2586) >> at >> org.apache.hadoop.hdfs.DFSClient$DFSOutputStream$DataStreamer.run(DFSClient.java:2790) >> >> >> >> I went through some old discussions and looks like manual rebalancing is >> what is required in this case and we should also have >> dfs.datanode.du.reserved set up. >> >> However I'd like to understand if this issue, with one disk getting >> filled up to 100% can result into the issue which we are seeing in our >> application. >> >> Also, are there any other peformance implications due to some of the >> disks running at 100% usage on a datanode. >> -- >> Mayank Joshi >> >> Skype: mail2mayank >> Mb.: +91 8690625808 >> >> Blog: http://www.techynfreesouls.co.nr >> PhotoStream: http://picasaweb.google.com/mail2mayank >> >> Today is tommorrow I was so worried about yesterday ... >> >> >> >> >> -- >> Nitin Pawar >> >> >> >> >> -- >> Mayank Joshi >> >> Skype: mail2mayank >> Mb.: +91 8690625808 >> >> Blog: http://www.techynfreesouls.co.nr >> PhotoStream: http://picasaweb.google.com/mail2mayank >> >> Today is tommorrow I was so worried about yesterday ... >> >> >> >> >> -- >> Nitin Pawar >> >> >> >> >> >> -- >> Mayank Joshi >> >> Skype: mail2mayank >> Mb.: +91 8690625808 >> >> Blog: http://www.techynfreesouls.co.nr >> PhotoStream: http://picasaweb.google.com/mail2mayank >> >> Today is tommorrow I was so worried about yesterday ... >> >> >> >> >> >> -- >> Mayank Joshi >> >> Skype: mail2mayank >> Mb.: +91 8690625808 >> >> Blog: http://www.techynfreesouls.co.nr >> PhotoStream: http://picasaweb.google.com/mail2mayank >> >> Today is tommorrow I was so worried about yesterday ... >> > >
