Re: Advice on restarting HDFS in a cron
You can also turn down the server logging level via bin/hadoop daemonlog -getlevel host:port server -setlevel host:port For the namenode 50070 For the jobtracker 50030 For the tasktracker 50060 For the secondary namenode 50090 For the datanode 50075 Somewhat wiser than I with log4j many have a better suggestion for the logger name to pick other than root., perhaps org.apache.hadoop. I beleve this, run from the master node would set the log level to warn for all the datanodes and tasktrackers for a in `cat conf/slaves`; do bin/hadoop daemonlog -setlevel $a:50075 root WARN; bin/hadoop daemonlog -setlevel $a:50060 root WARN; done and of course for the master node jobtracker and namenode bin/hadoop daemonlog -setlevel localhost:50030 root WARN bin/hadoop daemonlog -setlevel localhost:50070 root WARN On Sat, Apr 25, 2009 at 10:10 PM, Rakhi Khatwani rakhi.khatw...@gmail.comwrote: Thanks Aaron. On Sun, Apr 26, 2009 at 10:37 AM, Aaron Kimball aa...@cloudera.com wrote: If your logs were being written to the root partition (/dev/sda1), that's going to fill up fast. This partition is always = 10 GB on EC2 and much of that space is consumed by the OS install. You should redirect your logs to some place under /mnt (/dev/sdb1); that's 160 GB. - Aaron On Sun, Apr 26, 2009 at 3:21 AM, Rakhi Khatwani rakhi.khatw...@gmail.com wrote: Hi, I have faced somewhat a similar issue... i have a couple of map reduce jobs running on EC2... after a week or so, i get a no space on device exception while performing any linux command... so end up shuttin down hadoop and hbase, clear the logs and then restart them. is there a cleaner way to do it??? thanks Raakhi On Fri, Apr 24, 2009 at 11:59 PM, Todd Lipcon t...@cloudera.com wrote: On Fri, Apr 24, 2009 at 11:18 AM, Marc Limotte mlimo...@feeva.com wrote: Actually, I'm concerned about performance of map/reduce jobs for a long-running cluster. I.e. it seems to get slower the longer it's running. After a restart of HDFS, the jobs seems to run faster. Not concerned about the start-up time of HDFS. Hi Marc, Does it sound like this JIRA describes your problem? https://issues.apache.org/jira/browse/HADOOP-4766 If so, restarting just the JT should help with the symptoms. (I say symptoms because this is clearly a problem! Hadoop should be stable and performant for months without a cluster restart!) -Todd Of course, as you suggest, this could be poor configuration of the cluster on my part; but I'd still like to hear best practices around doing a scheduled restart. Marc -Original Message- From: Allen Wittenauer [mailto:a...@yahoo-inc.com] Sent: Friday, April 24, 2009 10:17 AM To: core-user@hadoop.apache.org Subject: Re: Advice on restarting HDFS in a cron On 4/24/09 9:31 AM, Marc Limotte mlimo...@feeva.com wrote: I've heard that HDFS starts to slow down after it's been running for a long time. And I believe I've experienced this. We did an upgrade (== complete restart) of a 2000 node instance in ~20 minutes on Wednesday. I wouldn't really consider that 'slow', but YMMV. I suspect people aren't running the secondary name node and therefore have massively large edits file. The name node appears slow on restart because it has to apply the edits to the fsimage rather than having the secondary keep it up to date. -Original Message- From: Marc Limotte Hi. I've heard that HDFS starts to slow down after it's been running for a long time. And I believe I've experienced this. So, I was thinking to set up a cron job to execute every week to shutdown HDFS and start it up again. In concept, it would be something like: 0 0 0 0 0 $HADOOP_HOME/bin/stop-dfs.sh; $HADOOP_HOME/bin/start-dfs.sh But I'm wondering if there is a safer way to do this. In particular: * What if a map/reduce job is running when this cron hits. Is there a way to suspend jobs while the HDFS restart happens? * Should I also restart the mapred daemons? * Should I wait some time after stop-dfs.sh for things to settle down, before executing start-dfs.sh? Or maybe I should run a command to verify that it is stopped before I run the start? Thanks for any help. Marc PRIVATE AND CONFIDENTIAL - NOTICE TO RECIPIENT: THIS E-MAIL IS MEANT FOR ONLY THE INTENDED RECIPIENT OF THE TRANSMISSION, AND MAY BE A COMMUNICATION PRIVILEGE BY LAW. IF YOU RECEIVED THIS E-MAIL IN ERROR, ANY REVIEW, USE, DISSEMINATION, DISTRIBUTION, OR COPYING OF THIS EMAIL
Re: Advice on restarting HDFS in a cron
Hi, I have faced somewhat a similar issue... i have a couple of map reduce jobs running on EC2... after a week or so, i get a no space on device exception while performing any linux command... so end up shuttin down hadoop and hbase, clear the logs and then restart them. is there a cleaner way to do it??? thanks Raakhi On Fri, Apr 24, 2009 at 11:59 PM, Todd Lipcon t...@cloudera.com wrote: On Fri, Apr 24, 2009 at 11:18 AM, Marc Limotte mlimo...@feeva.com wrote: Actually, I'm concerned about performance of map/reduce jobs for a long-running cluster. I.e. it seems to get slower the longer it's running. After a restart of HDFS, the jobs seems to run faster. Not concerned about the start-up time of HDFS. Hi Marc, Does it sound like this JIRA describes your problem? https://issues.apache.org/jira/browse/HADOOP-4766 If so, restarting just the JT should help with the symptoms. (I say symptoms because this is clearly a problem! Hadoop should be stable and performant for months without a cluster restart!) -Todd Of course, as you suggest, this could be poor configuration of the cluster on my part; but I'd still like to hear best practices around doing a scheduled restart. Marc -Original Message- From: Allen Wittenauer [mailto:a...@yahoo-inc.com] Sent: Friday, April 24, 2009 10:17 AM To: core-user@hadoop.apache.org Subject: Re: Advice on restarting HDFS in a cron On 4/24/09 9:31 AM, Marc Limotte mlimo...@feeva.com wrote: I've heard that HDFS starts to slow down after it's been running for a long time. And I believe I've experienced this. We did an upgrade (== complete restart) of a 2000 node instance in ~20 minutes on Wednesday. I wouldn't really consider that 'slow', but YMMV. I suspect people aren't running the secondary name node and therefore have massively large edits file. The name node appears slow on restart because it has to apply the edits to the fsimage rather than having the secondary keep it up to date. -Original Message- From: Marc Limotte Hi. I've heard that HDFS starts to slow down after it's been running for a long time. And I believe I've experienced this. So, I was thinking to set up a cron job to execute every week to shutdown HDFS and start it up again. In concept, it would be something like: 0 0 0 0 0 $HADOOP_HOME/bin/stop-dfs.sh; $HADOOP_HOME/bin/start-dfs.sh But I'm wondering if there is a safer way to do this. In particular: * What if a map/reduce job is running when this cron hits. Is there a way to suspend jobs while the HDFS restart happens? * Should I also restart the mapred daemons? * Should I wait some time after stop-dfs.sh for things to settle down, before executing start-dfs.sh? Or maybe I should run a command to verify that it is stopped before I run the start? Thanks for any help. Marc PRIVATE AND CONFIDENTIAL - NOTICE TO RECIPIENT: THIS E-MAIL IS MEANT FOR ONLY THE INTENDED RECIPIENT OF THE TRANSMISSION, AND MAY BE A COMMUNICATION PRIVILEGE BY LAW. IF YOU RECEIVED THIS E-MAIL IN ERROR, ANY REVIEW, USE, DISSEMINATION, DISTRIBUTION, OR COPYING OF THIS EMAIL IS STRICTLY PROHIBITED. PLEASE NOTIFY US IMMEDIATELY OF THE ERROR BY RETURN E-MAIL AND PLEASE DELETE THIS MESSAGE FROM YOUR SYSTEM.
Re: Advice on restarting HDFS in a cron
If your logs were being written to the root partition (/dev/sda1), that's going to fill up fast. This partition is always = 10 GB on EC2 and much of that space is consumed by the OS install. You should redirect your logs to some place under /mnt (/dev/sdb1); that's 160 GB. - Aaron On Sun, Apr 26, 2009 at 3:21 AM, Rakhi Khatwani rakhi.khatw...@gmail.comwrote: Hi, I have faced somewhat a similar issue... i have a couple of map reduce jobs running on EC2... after a week or so, i get a no space on device exception while performing any linux command... so end up shuttin down hadoop and hbase, clear the logs and then restart them. is there a cleaner way to do it??? thanks Raakhi On Fri, Apr 24, 2009 at 11:59 PM, Todd Lipcon t...@cloudera.com wrote: On Fri, Apr 24, 2009 at 11:18 AM, Marc Limotte mlimo...@feeva.com wrote: Actually, I'm concerned about performance of map/reduce jobs for a long-running cluster. I.e. it seems to get slower the longer it's running. After a restart of HDFS, the jobs seems to run faster. Not concerned about the start-up time of HDFS. Hi Marc, Does it sound like this JIRA describes your problem? https://issues.apache.org/jira/browse/HADOOP-4766 If so, restarting just the JT should help with the symptoms. (I say symptoms because this is clearly a problem! Hadoop should be stable and performant for months without a cluster restart!) -Todd Of course, as you suggest, this could be poor configuration of the cluster on my part; but I'd still like to hear best practices around doing a scheduled restart. Marc -Original Message- From: Allen Wittenauer [mailto:a...@yahoo-inc.com] Sent: Friday, April 24, 2009 10:17 AM To: core-user@hadoop.apache.org Subject: Re: Advice on restarting HDFS in a cron On 4/24/09 9:31 AM, Marc Limotte mlimo...@feeva.com wrote: I've heard that HDFS starts to slow down after it's been running for a long time. And I believe I've experienced this. We did an upgrade (== complete restart) of a 2000 node instance in ~20 minutes on Wednesday. I wouldn't really consider that 'slow', but YMMV. I suspect people aren't running the secondary name node and therefore have massively large edits file. The name node appears slow on restart because it has to apply the edits to the fsimage rather than having the secondary keep it up to date. -Original Message- From: Marc Limotte Hi. I've heard that HDFS starts to slow down after it's been running for a long time. And I believe I've experienced this. So, I was thinking to set up a cron job to execute every week to shutdown HDFS and start it up again. In concept, it would be something like: 0 0 0 0 0 $HADOOP_HOME/bin/stop-dfs.sh; $HADOOP_HOME/bin/start-dfs.sh But I'm wondering if there is a safer way to do this. In particular: * What if a map/reduce job is running when this cron hits. Is there a way to suspend jobs while the HDFS restart happens? * Should I also restart the mapred daemons? * Should I wait some time after stop-dfs.sh for things to settle down, before executing start-dfs.sh? Or maybe I should run a command to verify that it is stopped before I run the start? Thanks for any help. Marc PRIVATE AND CONFIDENTIAL - NOTICE TO RECIPIENT: THIS E-MAIL IS MEANT FOR ONLY THE INTENDED RECIPIENT OF THE TRANSMISSION, AND MAY BE A COMMUNICATION PRIVILEGE BY LAW. IF YOU RECEIVED THIS E-MAIL IN ERROR, ANY REVIEW, USE, DISSEMINATION, DISTRIBUTION, OR COPYING OF THIS EMAIL IS STRICTLY PROHIBITED. PLEASE NOTIFY US IMMEDIATELY OF THE ERROR BY RETURN E-MAIL AND PLEASE DELETE THIS MESSAGE FROM YOUR SYSTEM.
Re: Advice on restarting HDFS in a cron
Thanks Aaron. On Sun, Apr 26, 2009 at 10:37 AM, Aaron Kimball aa...@cloudera.com wrote: If your logs were being written to the root partition (/dev/sda1), that's going to fill up fast. This partition is always = 10 GB on EC2 and much of that space is consumed by the OS install. You should redirect your logs to some place under /mnt (/dev/sdb1); that's 160 GB. - Aaron On Sun, Apr 26, 2009 at 3:21 AM, Rakhi Khatwani rakhi.khatw...@gmail.com wrote: Hi, I have faced somewhat a similar issue... i have a couple of map reduce jobs running on EC2... after a week or so, i get a no space on device exception while performing any linux command... so end up shuttin down hadoop and hbase, clear the logs and then restart them. is there a cleaner way to do it??? thanks Raakhi On Fri, Apr 24, 2009 at 11:59 PM, Todd Lipcon t...@cloudera.com wrote: On Fri, Apr 24, 2009 at 11:18 AM, Marc Limotte mlimo...@feeva.com wrote: Actually, I'm concerned about performance of map/reduce jobs for a long-running cluster. I.e. it seems to get slower the longer it's running. After a restart of HDFS, the jobs seems to run faster. Not concerned about the start-up time of HDFS. Hi Marc, Does it sound like this JIRA describes your problem? https://issues.apache.org/jira/browse/HADOOP-4766 If so, restarting just the JT should help with the symptoms. (I say symptoms because this is clearly a problem! Hadoop should be stable and performant for months without a cluster restart!) -Todd Of course, as you suggest, this could be poor configuration of the cluster on my part; but I'd still like to hear best practices around doing a scheduled restart. Marc -Original Message- From: Allen Wittenauer [mailto:a...@yahoo-inc.com] Sent: Friday, April 24, 2009 10:17 AM To: core-user@hadoop.apache.org Subject: Re: Advice on restarting HDFS in a cron On 4/24/09 9:31 AM, Marc Limotte mlimo...@feeva.com wrote: I've heard that HDFS starts to slow down after it's been running for a long time. And I believe I've experienced this. We did an upgrade (== complete restart) of a 2000 node instance in ~20 minutes on Wednesday. I wouldn't really consider that 'slow', but YMMV. I suspect people aren't running the secondary name node and therefore have massively large edits file. The name node appears slow on restart because it has to apply the edits to the fsimage rather than having the secondary keep it up to date. -Original Message- From: Marc Limotte Hi. I've heard that HDFS starts to slow down after it's been running for a long time. And I believe I've experienced this. So, I was thinking to set up a cron job to execute every week to shutdown HDFS and start it up again. In concept, it would be something like: 0 0 0 0 0 $HADOOP_HOME/bin/stop-dfs.sh; $HADOOP_HOME/bin/start-dfs.sh But I'm wondering if there is a safer way to do this. In particular: * What if a map/reduce job is running when this cron hits. Is there a way to suspend jobs while the HDFS restart happens? * Should I also restart the mapred daemons? * Should I wait some time after stop-dfs.sh for things to settle down, before executing start-dfs.sh? Or maybe I should run a command to verify that it is stopped before I run the start? Thanks for any help. Marc PRIVATE AND CONFIDENTIAL - NOTICE TO RECIPIENT: THIS E-MAIL IS MEANT FOR ONLY THE INTENDED RECIPIENT OF THE TRANSMISSION, AND MAY BE A COMMUNICATION PRIVILEGE BY LAW. IF YOU RECEIVED THIS E-MAIL IN ERROR, ANY REVIEW, USE, DISSEMINATION, DISTRIBUTION, OR COPYING OF THIS EMAIL IS STRICTLY PROHIBITED. PLEASE NOTIFY US IMMEDIATELY OF THE ERROR BY RETURN E-MAIL AND PLEASE DELETE THIS MESSAGE FROM YOUR SYSTEM.
Advice on restarting HDFS in a cron
Hi. I've heard that HDFS starts to slow down after it's been running for a long time. And I believe I've experienced this. So, I was thinking to set up a cron job to execute every week to shutdown HDFS and start it up again. In concept, it would be something like: 0 0 0 0 0 $HADOOP_HOME/bin/stop-dfs.sh; $HADOOP_HOME/bin/start-dfs.sh But I'm wondering if there is a safer way to do this. In particular: * What if a map/reduce job is running when this cron hits. Is there a way to suspend jobs while the HDFS restart happens? * Should I also restart the mapred daemons? * Should I wait some time after stop-dfs.sh for things to settle down, before executing start-dfs.sh? Or maybe I should run a command to verify that it is stopped before I run the start? Thanks for any help. Marc PRIVATE AND CONFIDENTIAL - NOTICE TO RECIPIENT: THIS E-MAIL IS MEANT FOR ONLY THE INTENDED RECIPIENT OF THE TRANSMISSION, AND MAY BE A COMMUNICATION PRIVILEGE BY LAW. IF YOU RECEIVED THIS E-MAIL IN ERROR, ANY REVIEW, USE, DISSEMINATION, DISTRIBUTION, OR COPYING OF THIS EMAIL IS STRICTLY PROHIBITED. PLEASE NOTIFY US IMMEDIATELY OF THE ERROR BY RETURN E-MAIL AND PLEASE DELETE THIS MESSAGE FROM YOUR SYSTEM.
Re: Advice on restarting HDFS in a cron
On 4/24/09 9:31 AM, Marc Limotte mlimo...@feeva.com wrote: I've heard that HDFS starts to slow down after it's been running for a long time. And I believe I've experienced this. We did an upgrade (== complete restart) of a 2000 node instance in ~20 minutes on Wednesday. I wouldn't really consider that 'slow', but YMMV. I suspect people aren't running the secondary name node and therefore have massively large edits file. The name node appears slow on restart because it has to apply the edits to the fsimage rather than having the secondary keep it up to date.
RE: Advice on restarting HDFS in a cron
Actually, I'm concerned about performance of map/reduce jobs for a long-running cluster. I.e. it seems to get slower the longer it's running. After a restart of HDFS, the jobs seems to run faster. Not concerned about the start-up time of HDFS. Of course, as you suggest, this could be poor configuration of the cluster on my part; but I'd still like to hear best practices around doing a scheduled restart. Marc -Original Message- From: Allen Wittenauer [mailto:a...@yahoo-inc.com] Sent: Friday, April 24, 2009 10:17 AM To: core-user@hadoop.apache.org Subject: Re: Advice on restarting HDFS in a cron On 4/24/09 9:31 AM, Marc Limotte mlimo...@feeva.com wrote: I've heard that HDFS starts to slow down after it's been running for a long time. And I believe I've experienced this. We did an upgrade (== complete restart) of a 2000 node instance in ~20 minutes on Wednesday. I wouldn't really consider that 'slow', but YMMV. I suspect people aren't running the secondary name node and therefore have massively large edits file. The name node appears slow on restart because it has to apply the edits to the fsimage rather than having the secondary keep it up to date. -Original Message- From: Marc Limotte Hi. I've heard that HDFS starts to slow down after it's been running for a long time. And I believe I've experienced this. So, I was thinking to set up a cron job to execute every week to shutdown HDFS and start it up again. In concept, it would be something like: 0 0 0 0 0 $HADOOP_HOME/bin/stop-dfs.sh; $HADOOP_HOME/bin/start-dfs.sh But I'm wondering if there is a safer way to do this. In particular: * What if a map/reduce job is running when this cron hits. Is there a way to suspend jobs while the HDFS restart happens? * Should I also restart the mapred daemons? * Should I wait some time after stop-dfs.sh for things to settle down, before executing start-dfs.sh? Or maybe I should run a command to verify that it is stopped before I run the start? Thanks for any help. Marc PRIVATE AND CONFIDENTIAL - NOTICE TO RECIPIENT: THIS E-MAIL IS MEANT FOR ONLY THE INTENDED RECIPIENT OF THE TRANSMISSION, AND MAY BE A COMMUNICATION PRIVILEGE BY LAW. IF YOU RECEIVED THIS E-MAIL IN ERROR, ANY REVIEW, USE, DISSEMINATION, DISTRIBUTION, OR COPYING OF THIS EMAIL IS STRICTLY PROHIBITED. PLEASE NOTIFY US IMMEDIATELY OF THE ERROR BY RETURN E-MAIL AND PLEASE DELETE THIS MESSAGE FROM YOUR SYSTEM.
Re: Advice on restarting HDFS in a cron
On Fri, Apr 24, 2009 at 11:18 AM, Marc Limotte mlimo...@feeva.com wrote: Actually, I'm concerned about performance of map/reduce jobs for a long-running cluster. I.e. it seems to get slower the longer it's running. After a restart of HDFS, the jobs seems to run faster. Not concerned about the start-up time of HDFS. Hi Marc, Does it sound like this JIRA describes your problem? https://issues.apache.org/jira/browse/HADOOP-4766 If so, restarting just the JT should help with the symptoms. (I say symptoms because this is clearly a problem! Hadoop should be stable and performant for months without a cluster restart!) -Todd Of course, as you suggest, this could be poor configuration of the cluster on my part; but I'd still like to hear best practices around doing a scheduled restart. Marc -Original Message- From: Allen Wittenauer [mailto:a...@yahoo-inc.com] Sent: Friday, April 24, 2009 10:17 AM To: core-user@hadoop.apache.org Subject: Re: Advice on restarting HDFS in a cron On 4/24/09 9:31 AM, Marc Limotte mlimo...@feeva.com wrote: I've heard that HDFS starts to slow down after it's been running for a long time. And I believe I've experienced this. We did an upgrade (== complete restart) of a 2000 node instance in ~20 minutes on Wednesday. I wouldn't really consider that 'slow', but YMMV. I suspect people aren't running the secondary name node and therefore have massively large edits file. The name node appears slow on restart because it has to apply the edits to the fsimage rather than having the secondary keep it up to date. -Original Message- From: Marc Limotte Hi. I've heard that HDFS starts to slow down after it's been running for a long time. And I believe I've experienced this. So, I was thinking to set up a cron job to execute every week to shutdown HDFS and start it up again. In concept, it would be something like: 0 0 0 0 0 $HADOOP_HOME/bin/stop-dfs.sh; $HADOOP_HOME/bin/start-dfs.sh But I'm wondering if there is a safer way to do this. In particular: * What if a map/reduce job is running when this cron hits. Is there a way to suspend jobs while the HDFS restart happens? * Should I also restart the mapred daemons? * Should I wait some time after stop-dfs.sh for things to settle down, before executing start-dfs.sh? Or maybe I should run a command to verify that it is stopped before I run the start? Thanks for any help. Marc PRIVATE AND CONFIDENTIAL - NOTICE TO RECIPIENT: THIS E-MAIL IS MEANT FOR ONLY THE INTENDED RECIPIENT OF THE TRANSMISSION, AND MAY BE A COMMUNICATION PRIVILEGE BY LAW. IF YOU RECEIVED THIS E-MAIL IN ERROR, ANY REVIEW, USE, DISSEMINATION, DISTRIBUTION, OR COPYING OF THIS EMAIL IS STRICTLY PROHIBITED. PLEASE NOTIFY US IMMEDIATELY OF THE ERROR BY RETURN E-MAIL AND PLEASE DELETE THIS MESSAGE FROM YOUR SYSTEM.
