There is no ntpupdate command. You can update ntp by typing # ntpdate -u {Main node sync'ed to NTP server IP address or Domain name here} Example # ntpdate -u domains.ntp.com OR # ntpdate -u 192.168.0.2 You should only have 1 node announcing NTP and other nodes getting time from main node. ... View more

I use puppet and foreman to configure each system the same for all ntp clients to a central ntp server. Great information here http://www.linuxsecrets.com/blog/4tutorial-and-install-howto/2014/06/26/906-how-to-install-and-configure-linux-ntp-server-and-client ... View more

Hi anton_85   Try this article, it explains time zones and settings which is very well explained.   http://www.linuxsecrets.com/easyblog/2015/01/30/1374-fixing-date-and-setting-time-and-zone-on-rhel-6-from-command-line     ... View more

Hi eafonsof   Updating your kernel version will resolve the issue most likely.   I updated mine to kernel 3.18.x and resolved the issue. ... View more

I'll work on the documentation this weekend   Something you can understand without having to click another link,link, link to find information :-). ... View more

I can document the process for CentOS if you like. It's pretty much the same with RedHat as well.  Only difference is the repo and versions.   Let me know if you want it documented then I'll post it somewhere for you. ... View more

P.S. Don't forget to create or move your current .config from previous kernel or create new .config. # cd /usr/src/kernels/linux-3.18.8 # cp ../linux-old-kernel-version/.config . # make oldconfig -j32;make modules -j32;make modules_install -j32;make install # Answer all question using just the default. Just enter through the kernel questions. ... View more

Just change the versioning number from kernel or update to RedHat 6.6.  6.6 works perfectly.  Down grading isn't a good option in my opinion.   It's simply needs a version check which you can do by just upgrading the kernel version.   Easiest way instead of doing a complete reinstall or downgrade which isn't a good option.   Download kernel from kernel.org   # cd /usr/src/kernels   # wget https://www.kernel.org/pub/linux/kernel/v3.x/linux-3.18.8.tar.gz   # tar zxvf  linux-3.18.8.tar.gz   # cd linux-3.18.8   # make -j32;make modules -j32;make modules_install -j32;make install   # edit /boot/grub/grub.cfg   Change to 0 which is the current kernel version and that's it, reboot and you're set. ... View more

I found a way to increase network performance but only for write. When I run a read dfsio it only seems to be sending to the local drive from 1 system and not reading from multiple systems. I need the system to read through the network and not locally can any body help on how to force network reads using dfsio? ... View more

I found this article which was super helpful.   http://www.linuxsecrets.com/categories/linux-performance/performance-tips/redhat-prerequisites-benchmarking-and-stress-testing-on-hadoop-cluster ... View more

I would also like to cut down on local hhd writes so I can evenly distribute data to all machines so I get more network traffic as well.   @nauseous wrote: I'm trying to get maximum throughput with Cloudera on RedHat 6.6 on 6 - Dell R730's with kernel 3.18.1, and using 2 - 850MB, 3G ssd transfer per second hhd with modified drivers which have been tested. Currently I've tried decommissioning "mapReduce tasktracker" on all nodes except 1 single node as suggested but didn't really make any differences in nic speed. I want to max out the connection speed on all nodes if possible.   I've tried : sudo -u hdfs hadoop jar /opt/cloudera/parcels/CDH-5.3.1-1.cdh5.3.1.p0.5/jars/hadoop-test-2.5.0-mr1-cdh5.3.1.jar  TestDFSIO -write -nrFiles 100000 -fileSize 50   and    sudo -u hdfs hadoop jar /opt/cloudera/parcels/CDH-5.3.1-1.cdh5.3.1.p0.5/jars/hadoop-test-2.5.0-mr1-cdh5.3.1.jar  TestDFSIO -write -nrFiles 500 -fileSize 10GB   without good results.   I've already tested throughput with netperf but can't seem to get cloudera to perform network tests to maximum level like I have with netperf using dfsio.     Any suggestions would help greatly.     @nauseous wrote: I'm trying to get maximum throughput with Cloudera on RedHat 6.6 on 6 - Dell R730's with kernel 3.18.1, and using 2 - 850MB, 3G ssd transfer per second hhd with modified drivers which have been tested. Currently I've tried decommissioning "mapReduce tasktracker" on all nodes except 1 single node as suggested but didn't really make any differences in nic speed. I want to max out the connection speed on all nodes if possible.   I've tried : sudo -u hdfs hadoop jar /opt/cloudera/parcels/CDH-5.3.1-1.cdh5.3.1.p0.5/jars/hadoop-test-2.5.0-mr1-cdh5.3.1.jar  TestDFSIO -write -nrFiles 100000 -fileSize 50   and    sudo -u hdfs hadoop jar /opt/cloudera/parcels/CDH-5.3.1-1.cdh5.3.1.p0.5/jars/hadoop-test-2.5.0-mr1-cdh5.3.1.jar  TestDFSIO -write -nrFiles 500 -fileSize 10GB   without good results.   I've already tested throughput with netperf but can't seem to get cloudera to perform network tests to maximum level like I have with netperf using dfsio.     Any suggestions would help greatly.     ... View more

I wasn't able to find my post sense I don't have my machine but here is a great article here http://tinyurl.com/lr3gfx4   Hope this helps 🙂 ... View more

Great job.   I try to keep the names as simple as possible so I can run thousands of scripts.   My hosts files is like:   127.0.0.1     localhost   Looping interfaces from multiple machines. AWS or for example Linode looping you just would use the internal looping device. Fast and quickly managed.   #Cloudera Machines   192.168.2.1     n1 192.168.2.2     n2 192.168.2.3     n3          "              n4          "              n5          "              n6          "              n7   and so on to make it easier for changes across machines.   Such as:   for i in {1..300}; do ssh n$i date; done   <-- Checks dates on all machines to make sure each machine is sync'ed.   Makes life easier to make it simple. ... View more

Great job.   I try to keep the names as simple as possible so I can run thousands of scripts.   My hosts files is like:   127.0.0.1   ... View more

Sounds like your nsswitch is wrong.  It should be "files dns" not "dns files".   I would definately check it out and verify you don't have it setup wrong. ... View more

I've install it to RedHat 6.6 and works perfectly without issues.     I actually created an article with prerequisites and they just posted it if you need that link let me know.     ... View more