Re: dynamically resizing the Hadoop cluster?
It seems like you may want to look into Amazon's EMR (elastic mapreduce), which does much of what you are trying to do. It's worth taking a look at since you're already storing your data in S3 and using EC2 for your cluster(s). On Thu, Oct 24, 2013 at 5:07 PM, Nan Zhu wrote: > Good explanation, > > Thank you, Ravi > > Best, > > > On Thu, Oct 24, 2013 at 4:51 PM, Ravi Prakash wrote: > >> Hi Nan! >> >> If the task trackers stop heartbeating back to the JobTracker, the >> JobTracker will mark them as dead and reschedule the tasks which were >> running on that TaskTracker. Admittedly there is some delay between when >> the TaskTrackers stop heartbeating back and when the JobTracker marks them >> dead. This is controlled by the mapred.tasktracker.expiry.intervalparameter >> (I'm assuming you are using Hadoop 1.x) >> >> HTH >> Ravi >> >> >> >> >> >> >> On Thursday, October 24, 2013 1:21 PM, Nan Zhu >> wrote: >> Hi, Ravi, >> >> Thank you for the reply >> >> Actually I'm not running HDFS on EC2, instead I use S3 to store data >> >> I'm curious about that, if some nodes are decommissioned, the JobTracker >> will deal those tasks which originally ran on them as "too slow" (since no >> progress for a long time) so to run speculative execution OR it directly >> treats them as "belonging to a running Job and ran on a dead TaskTracker"? >> >> Best, >> >> Nan >> >> >> >> >> >> >> On Thu, Oct 24, 2013 at 2:04 PM, Ravi Prakash wrote: >> >> Hi Nan! >> >> Usually nodes are decommissioned slowly over some period of time so as >> not to disrupt the running jobs. When a node is decommissioned, the >> NameNode must re-replicate all under-replicated blocks. Rather than >> suddenly remove half the nodes, you might want to take a few nodes offline >> at a time. Hadoop should be able to handle rescheduling tasks on nodes no >> longer available (even without speculative execution. Speculative execution >> is for something else). >> >> HTH >> Ravi >> >> >> On Wednesday, October 23, 2013 10:26 PM, Nan Zhu >> wrote: >> Hi, all >> >> I’m running a Hadoop cluster on AWS EC2, >> >> I would like to dynamically resizing the cluster so as to reduce the >> cost, is there any solution to achieve this? >> >> E.g. I would like to cut the cluster size with a half, is it safe to just >> shutdown the instances (if some tasks are just running on them, can I rely >> on the speculative execution to re-run them on the other nodes?) >> >> I cannot use EMR, since I’m running a customized version of Hadoop >> >> Best, >> >> -- >> Nan Zhu >> School of Computer Science, >> McGill University >> >> >> >> >> >> >> >> -- >> Nan Zhu >> School of Computer Science, >> McGill University >> E-Mail: zhunanmcg...@gmail.com >> >> >> > > > -- > Nan Zhu > School of Computer Science, > McGill University > E-Mail: zhunanmcg...@gmail.com >
Re: dynamically resizing the Hadoop cluster?
Good explanation, Thank you, Ravi Best, On Thu, Oct 24, 2013 at 4:51 PM, Ravi Prakash wrote: > Hi Nan! > > If the task trackers stop heartbeating back to the JobTracker, the > JobTracker will mark them as dead and reschedule the tasks which were > running on that TaskTracker. Admittedly there is some delay between when > the TaskTrackers stop heartbeating back and when the JobTracker marks them > dead. This is controlled by the mapred.tasktracker.expiry.intervalparameter > (I'm assuming you are using Hadoop 1.x) > > HTH > Ravi > > > > > > > On Thursday, October 24, 2013 1:21 PM, Nan Zhu > wrote: > Hi, Ravi, > > Thank you for the reply > > Actually I'm not running HDFS on EC2, instead I use S3 to store data > > I'm curious about that, if some nodes are decommissioned, the JobTracker > will deal those tasks which originally ran on them as "too slow" (since no > progress for a long time) so to run speculative execution OR it directly > treats them as "belonging to a running Job and ran on a dead TaskTracker"? > > Best, > > Nan > > > > > > > On Thu, Oct 24, 2013 at 2:04 PM, Ravi Prakash wrote: > > Hi Nan! > > Usually nodes are decommissioned slowly over some period of time so as not > to disrupt the running jobs. When a node is decommissioned, the NameNode > must re-replicate all under-replicated blocks. Rather than suddenly remove > half the nodes, you might want to take a few nodes offline at a time. > Hadoop should be able to handle rescheduling tasks on nodes no longer > available (even without speculative execution. Speculative execution is for > something else). > > HTH > Ravi > > > On Wednesday, October 23, 2013 10:26 PM, Nan Zhu > wrote: > Hi, all > > I’m running a Hadoop cluster on AWS EC2, > > I would like to dynamically resizing the cluster so as to reduce the cost, > is there any solution to achieve this? > > E.g. I would like to cut the cluster size with a half, is it safe to just > shutdown the instances (if some tasks are just running on them, can I rely > on the speculative execution to re-run them on the other nodes?) > > I cannot use EMR, since I’m running a customized version of Hadoop > > Best, > > -- > Nan Zhu > School of Computer Science, > McGill University > > > > > > > > -- > Nan Zhu > School of Computer Science, > McGill University > E-Mail: zhunanmcg...@gmail.com > > > -- Nan Zhu School of Computer Science, McGill University E-Mail: zhunanmcg...@gmail.com
Re: dynamically resizing the Hadoop cluster?
Hi Nan! If the task trackers stop heartbeating back to the JobTracker, the JobTracker will mark them as dead and reschedule the tasks which were running on that TaskTracker. Admittedly there is some delay between when the TaskTrackers stop heartbeating back and when the JobTracker marks them dead. This is controlled by the mapred.tasktracker.expiry.interval parameter (I'm assuming you are using Hadoop 1.x) HTH Ravi On Thursday, October 24, 2013 1:21 PM, Nan Zhu wrote: Hi, Ravi, Thank you for the reply Actually I'm not running HDFS on EC2, instead I use S3 to store data I'm curious about that, if some nodes are decommissioned, the JobTracker will deal those tasks which originally ran on them as "too slow" (since no progress for a long time) so to run speculative execution OR it directly treats them as "belonging to a running Job and ran on a dead TaskTracker"? Best, Nan On Thu, Oct 24, 2013 at 2:04 PM, Ravi Prakash wrote: Hi Nan! > > >Usually nodes are decommissioned slowly over some period of time so as not to >disrupt the running jobs. When a node is decommissioned, the NameNode must >re-replicate all under-replicated blocks. Rather than suddenly remove half the >nodes, you might want to take a few nodes offline at a time. Hadoop should be >able to handle rescheduling tasks on nodes no longer available (even without >speculative execution. Speculative execution is for something else). > > > >HTH >Ravi > > > > >On Wednesday, October 23, 2013 10:26 PM, Nan Zhu wrote: > >Hi, all > > >I’m running a Hadoop cluster on AWS EC2, > > >I would like to dynamically resizing the cluster so as to reduce the cost, is >there any solution to achieve this? > > >E.g. I would like to cut the cluster size with a half, is it safe to just >shutdown the instances (if some tasks are just running on them, can I rely on >the speculative execution to re-run them on the other nodes?) > > >I cannot use EMR, since I’m running a customized version of Hadoop > > >Best, > > >-- >Nan Zhu >School of Computer Science, >McGill University > > > > > > -- Nan Zhu School of Computer Science, McGill University E-Mail: zhunanmcg...@gmail.com
Re: dynamically resizing the Hadoop cluster?
Hi, Ravi, Thank you for the reply Actually I'm not running HDFS on EC2, instead I use S3 to store data I'm curious about that, if some nodes are decommissioned, the JobTracker will deal those tasks which originally ran on them as "too slow" (since no progress for a long time) so to run speculative execution OR it directly treats them as "belonging to a running Job and ran on a dead TaskTracker"? Best, Nan On Thu, Oct 24, 2013 at 2:04 PM, Ravi Prakash wrote: > Hi Nan! > > Usually nodes are decommissioned slowly over some period of time so as not > to disrupt the running jobs. When a node is decommissioned, the NameNode > must re-replicate all under-replicated blocks. Rather than suddenly remove > half the nodes, you might want to take a few nodes offline at a time. > Hadoop should be able to handle rescheduling tasks on nodes no longer > available (even without speculative execution. Speculative execution is for > something else). > > HTH > Ravi > > > On Wednesday, October 23, 2013 10:26 PM, Nan Zhu > wrote: > Hi, all > > I’m running a Hadoop cluster on AWS EC2, > > I would like to dynamically resizing the cluster so as to reduce the cost, > is there any solution to achieve this? > > E.g. I would like to cut the cluster size with a half, is it safe to just > shutdown the instances (if some tasks are just running on them, can I rely > on the speculative execution to re-run them on the other nodes?) > > I cannot use EMR, since I’m running a customized version of Hadoop > > Best, > > -- > Nan Zhu > School of Computer Science, > McGill University > > > > > -- Nan Zhu School of Computer Science, McGill University E-Mail: zhunanmcg...@gmail.com
Re: dynamically resizing the Hadoop cluster?
Hi Nan! Usually nodes are decommissioned slowly over some period of time so as not to disrupt the running jobs. When a node is decommissioned, the NameNode must re-replicate all under-replicated blocks. Rather than suddenly remove half the nodes, you might want to take a few nodes offline at a time. Hadoop should be able to handle rescheduling tasks on nodes no longer available (even without speculative execution. Speculative execution is for something else). HTH Ravi On Wednesday, October 23, 2013 10:26 PM, Nan Zhu wrote: Hi, all I’m running a Hadoop cluster on AWS EC2, I would like to dynamically resizing the cluster so as to reduce the cost, is there any solution to achieve this? E.g. I would like to cut the cluster size with a half, is it safe to just shutdown the instances (if some tasks are just running on them, can I rely on the speculative execution to re-run them on the other nodes?) I cannot use EMR, since I’m running a customized version of Hadoop Best, -- Nan Zhu School of Computer Science, McGill University
dynamically resizing the Hadoop cluster?
Hi, all I’m running a Hadoop cluster on AWS EC2, I would like to dynamically resizing the cluster so as to reduce the cost, is there any solution to achieve this? E.g. I would like to cut the cluster size with a half, is it safe to just shutdown the instances (if some tasks are just running on them, can I rely on the speculative execution to re-run them on the other nodes?) I cannot use EMR, since I’m running a customized version of Hadoop Best, -- Nan Zhu School of Computer Science, McGill University
